Arabidopsis alcohol dehydrogenase expression in both shoots and roots is conditioned by root growth environment

NASA Technical Reports Server (NTRS)

Chung, H. J.; Ferl, R. J.

1999-01-01

It is widely accepted that the Arabidopsis Adh (alcohol dehydrogenase) gene is constitutively expressed at low levels in the roots of young plants grown on agar media, and that the expression level is greatly induced by anoxic or hypoxic stresses. We questioned whether the agar medium itself created an anaerobic environment for the roots upon their growing into the gel. beta-Glucuronidase (GUS) expression driven by the Adh promoter was examined by growing transgenic Arabidopsis plants in different growing systems. Whereas roots grown on horizontal-positioned plates showed high Adh/GUS expression levels, roots from vertical-positioned plates had no Adh/GUS expression. Additional results indicate that growth on vertical plates closely mimics the Adh/GUS expression observed for soil-grown seedlings, and that growth on horizontal plates results in induction of high Adh/GUS expression that is consistent with hypoxic or anoxic conditions within the agar of the root zone. Adh/GUS expression in the shoot apex is also highly induced by root penetration of the agar medium. This induction of Adh/GUS in shoot apex and roots is due, at least in part, to mechanisms involving Ca2+ signal transduction.

Root interaction between Bromud tectorum and Poa pratensis: a three-dimensional analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bookman, P.A.; Mack, R.N.

1982-06-01

The spatial distribution of roots of two alien grasses, Bromus tectorum and Poa pratensis, grown singly and in a mixture, was examined using a double-labelling radioisotope technique. Interactions between the root systems of these plants led to a restricted B. tectorum rooting volume in P. pratensis neighborhoods greater than or equal to30-d-old. The roots of B. tectorum failed to develop laterally. The altered B. tectorum root systems may contribute to its inability to persist in established P. pratensis swards.

Gravisensitivity and automorphogenesis of lentil seedling roots grown on board the International Space Station.

PubMed

Driss-Ecole, Dominique; Legué, Valérie; Carnero-Diaz, Eugénie; Perbal, Gérald

2008-09-01

The GRAVI-1 experiment was brought on board the International Space Station by Discovery (December 2006) and carried out in January 2007 in the European Modular Cultivation System facility. For the first run of this experiment, lentil seedlings were hydrated and grown in microgravity for 15 h and then subjected for 13 h 40 min to centrifugal accelerations ranging from 0.29 x 10(-2) g to 0.99 x 10(-2) g. During the second run, seedlings were grown either for 30 h 30 min in microgravity (this sample was the control) or for 21 h 30 min and then subjected to centrifugal accelerations ranging from 1.2 x 10(-2) g to 2.0 x 10(-2) g for 9 h. In both cases, root orientation and root curvature were followed by time-lapse photography. Still images were downlinked in near real time to ground Norwegian User Support and Operations Center during the experiment. The position of the root tip and the root curvature were analyzed as a function of time. It has been shown that in microgravity, the embryonic root curved strongly away from the cotyledons (automorphogenesis) and then straightened out slowly from 17 to 30 h following hydration (autotropism). Because of the autotropic straightening of roots in microgravity, their tip was oriented at an angle close to the optimal angle of curvature (120 degrees -135 degrees ) for a period of 2 h during centrifugation. Moreover, it has been demonstrated that lentil roots grown in microgravity before stimulation were more sensitive than roots grown in 1 g. In these conditions, the threshold acceleration perceived by these organs was found to be between 0 and 2.0 x 10(-3) g and estimated punctually at 1.4 x 10(-5) g by using the hyperbolic model for fitting the experimental data and by assuming that autotropism had no or little impact on the gravitropic response. Gravisensing by statoliths should be possible at such a low level of acceleration because the actomyosin system could provide the necessary work to overcome the activation energy for gravisensing.

Root-zone temperature and nitrogen affect the yield and secondary metabolite concentration of fall- and spring-grown, high-density leaf lettuce.

PubMed

Bumgarner, Natalie R; Scheerens, Joseph C; Mullen, Robert W; Bennett, Mark A; Ling, Peter P; Kleinhenz, Matthew D

2012-01-15

Understanding the effects of temperature and nitrogen levels on key variables, particularly under field conditions during cool seasons of temperate climates, is important. Here, we document the impact of root-zone heating and nitrogen (N) fertility on the accumulation and composition of fall- and spring-grown lettuce biomass. A novel, scalable field system was employed. Direct-seeded plots containing a uniform, semi-solid, and nearly stable rooting medium were established outdoors in 2009 and 2010; each contained one of eight combinations of root-zone heating (-/+) and N fertility (0, 72, 144, and 576 mg day(-1)). Root-zone heating increased but withholding N decreased biomass accumulation in both years. Low N supplies were also associated with greater anthocyanin and total antioxidant power but lower N and phosphorus levels. Tissue chlorophyll a and vitamin C levels tracked root-zone temperature and N fertility more closely in 2009 and 2010, respectively. Experimentally imposed root-zone temperature and N levels influenced the amount and properties of fall- and spring-grown lettuce tissue. Ambient conditions, however, dictated which of these factors exerted the greatest effect on the variables measured. Collectively, the results point to the potential for gains in system sustainability and productivity, including with respect to supplying human nutritional units. Copyright © 2011 Society of Chemical Industry.

Influence of shading on container-grown flowering dogwoods

USDA-ARS?s Scientific Manuscript database

Bare root dogwoods can be successfully grown when transplanted into a container production system. Shade treatments regardless of color or density did have an effect on the plant growth of Cherokee Brave™ and Cherokee Princess dogwood. Plants grown under 50% black and 50% white shade had more heigh...

Root-shoot allometry of tropical forest trees determined in a large-scale aeroponic system.

PubMed

Eshel, Amram; Grünzweig, José M

2013-07-01

This study is a first step in a multi-stage project aimed at determining allometric relationships among the tropical tree organs, and carbon fluxes between the various tree parts and their environment. Information on canopy-root interrelationships is needed to improve understanding of above- and below-ground processes and for modelling of the regional and global carbon cycle. Allometric relationships between the sizes of different plant parts will be determined. Two tropical forest species were used in this study: Ceiba pentandra (kapok), a fast-growing tree native to South and Central America and to Western Africa, and Khaya anthotheca (African mahogany), a slower-growing tree native to Central and Eastern Africa. Growth and allometric parameters of 12-month-old saplings grown in a large-scale aeroponic system and in 50-L soil containers were compared. The main advantage of growing plants in aeroponics is that their root systems are fully accessible throughout the plant life, and can be fully recovered for harvesting. The expected differences in shoot and root size between the fast-growing C. pentandra and the slower-growing K. anthotheca were evident in both growth systems. Roots were recovered from the aeroponically grown saplings only, and their distribution among various diameter classes followed the patterns expected from the literature. Stem, branch and leaf allometric parameters were similar for saplings of each species grown in the two systems. The aeroponic tree growth system can be utilized for determining the basic allometric relationships between root and shoot components of these trees, and hence can be used to study carbon allocation and fluxes of whole above- and below-ground tree parts.

Status of porous tube plant growth unit research - Development of a plant nutrient delivery system for space

NASA Technical Reports Server (NTRS)

Dreschel, T. W.; Wheeler, R. M.; Sager, J. C.

1988-01-01

A system developed for plant production in space was used to grow wheat, beans, rice, and white potatoes. It was found that the negative gauge pressure used to control the nutrient solution at the root/membrane interface and the pore size influence plant production. The results suggest that wheat, rice, beans, and lettuce can probably be grown with production values resembling those of plants grown in other media. Potato growth seemed to be stunted; this could be a possible response to root restriction.

An endogenous growth pattern of roots is revealed in seedlings grown in microgravity.

PubMed

Millar, Katherine D L; Johnson, Christina M; Edelmann, Richard E; Kiss, John Z

2011-10-01

In plants, sensitive and selective mechanisms have evolved to perceive and respond to light and gravity. We investigated the effects of microgravity on the growth and development of Arabidopsis thaliana (ecotype Landsberg) in a spaceflight experiment. These studies were performed with the Biological Research in Canisters (BRIC) hardware system in the middeck region of the space shuttle during mission STS-131 in April 2010. Seedlings were grown on nutrient agar in Petri dishes in BRIC hardware under dark conditions and then fixed in flight with paraformaldehyde, glutaraldehyde, or RNAlater. Although the long-term objective was to study the role of the actin cytoskeleton in gravity perception, in this article we focus on the analysis of morphology of seedlings that developed in microgravity. While previous spaceflight studies noted deleterious morphological effects due to the accumulation of ethylene gas, no such effects were observed in seedlings grown with the BRIC system. Seed germination was 89% in the spaceflight experiment and 91% in the ground control, and seedlings grew equally well in both conditions. However, roots of space-grown seedlings exhibited a significant difference (compared to the ground controls) in overall growth patterns in that they skewed to one direction. In addition, a greater number of adventitious roots formed from the axis of the hypocotyls in the flight-grown plants. Our hypothesis is that an endogenous response in plants causes the roots to skew and that this default growth response is largely masked by the normal 1 g conditions on Earth.

Interaction of Vesicular-arbuscular Mycorrhizal Fungi and Phosphorus with Meloidogyne incognita on Tomato.

PubMed

Cason, K M; Hussey, R S; Roncadori, R W

1983-07-01

The influence of two vesicular-arbuscular mycorrhizal fungi and phosphorus (P) nutrition on penetration, development, and reproduction by Meloidogyne incognita on Walter tomato was studied in the greenhouse. Inoculation with either Gigaspora margarita or Glomus mosseae 2 wk prior to nematode inoculation did not alter infection by M. incognita compared with nonmycorrhizal plants, regardless of soil P level (either 3 mug [low P] or 30 mug [high P] available P/g soil). At a given soil P level, nematode penetration and reproduction did not differ in mycorrhizal and nonmycorrhizal plants. However, plants grown in high P soil had greater root weights, increased nematode penetration and egg production per plant, and decreased colonization by mycorrhizal fungi, compared with plants grown in low P soil. The number of eggs per female nematode on mycorrhizal and nonmycorrhizal plants was not influenced by P treatment. Tomato plants with split root systems grown in double-compartment containers which had either low P soil in both sides or high P in one side and low P in the other, were inoculated at transplanting with G. margarita and 2 wk later one-half of the split root system of each plant was inoculated with M. incognita larvae. Although the mycoorhizal fungus increased the inorganic P content of the root to a level comparable to that in plants grown in high P soil, nematode penetration and reproduction were not altered. In a third series of experiments, the rate of nematode development was not influenced by either the presence of G. margarita or high soil P, compared with control plants grown in low P soil. These data indicate that supplemental P (30 mu/g soil) alters root-knot nematode infection of tomato more than G. mosseae and G. margarita.

Do root hydraulic properties change during the early vegetative stage of plant development in barley (Hordeum vulgare)?

PubMed Central

Suku, Shimi; Knipfer, Thorsten; Fricke, Wieland

2014-01-01

Background and Aims As annual crops develop, transpirational water loss increases substantially. This increase has to be matched by an increase in water uptake through the root system. The aim of this study was to assess the contributions of changes in intrinsic root hydraulic conductivity (Lp, water uptake per unit root surface area, driving force and time), driving force and root surface area to developmental increases in root water uptake. Methods Hydroponically grown barley plants were analysed during four windows of their vegetative stage of development, when they were 9–13, 14–18, 19–23 and 24–28 d old. Hydraulic conductivity was determined for individual roots (Lp) and for entire root systems (Lpr). Osmotic Lp of individual seminal and adventitious roots and osmotic Lpr of the root system were determined in exudation experiments. Hydrostatic Lp of individual roots was determined by root pressure probe analyses, and hydrostatic Lpr of the root system was derived from analyses of transpiring plants. Key Results Although osmotic and hydrostatic Lp and Lpr values increased initially during development and were correlated positively with plant transpiration rate, their overall developmental increases (about 2-fold) were small compared with increases in transpirational water loss and root surface area (about 10- to 40-fold). The water potential gradient driving water uptake in transpiring plants more than doubled during development, and potentially contributed to the increases in plant water flow. Osmotic Lpr of entire root systems and hydrostatic Lpr of transpiring plants were similar, suggesting that the main radial transport path in roots was the cell-to-cell path at all developmental stages. Conclusions Increase in the surface area of root system, and not changes in intrinsic root hydraulic properties, is the main means through which barley plants grown hydroponically sustain an increase in transpirational water loss during their vegetative development. PMID:24287810

Do root hydraulic properties change during the early vegetative stage of plant development in barley (Hordeum vulgare)?

PubMed

Suku, Shimi; Knipfer, Thorsten; Fricke, Wieland

2014-02-01

As annual crops develop, transpirational water loss increases substantially. This increase has to be matched by an increase in water uptake through the root system. The aim of this study was to assess the contributions of changes in intrinsic root hydraulic conductivity (Lp, water uptake per unit root surface area, driving force and time), driving force and root surface area to developmental increases in root water uptake. Hydroponically grown barley plants were analysed during four windows of their vegetative stage of development, when they were 9-13, 14-18, 19-23 and 24-28 d old. Hydraulic conductivity was determined for individual roots (Lp) and for entire root systems (Lp(r)). Osmotic Lp of individual seminal and adventitious roots and osmotic Lp(r) of the root system were determined in exudation experiments. Hydrostatic Lp of individual roots was determined by root pressure probe analyses, and hydrostatic Lp(r) of the root system was derived from analyses of transpiring plants. Although osmotic and hydrostatic Lp and Lp(r) values increased initially during development and were correlated positively with plant transpiration rate, their overall developmental increases (about 2-fold) were small compared with increases in transpirational water loss and root surface area (about 10- to 40-fold). The water potential gradient driving water uptake in transpiring plants more than doubled during development, and potentially contributed to the increases in plant water flow. Osmotic Lp(r) of entire root systems and hydrostatic Lp(r) of transpiring plants were similar, suggesting that the main radial transport path in roots was the cell-to-cell path at all developmental stages. Increase in the surface area of root system, and not changes in intrinsic root hydraulic properties, is the main means through which barley plants grown hydroponically sustain an increase in transpirational water loss during their vegetative development.

Effect of Rice Cultivation Systems on Indigenous Arbuscular Mycorrhizal Fungal Community Structure

PubMed Central

Watanarojanaporn, Nantida; Boonkerd, Nantakorn; Tittabutr, Panlada; Longtonglang, Aphakorn; Young, J. Peter W.; Teaumroong, Neung

2013-01-01

Arbuscular mycorrhizal fungi (AMF) in an agricultural ecosystem are necessary for proper management of beneficial symbiosis. Here we explored how the patterns of the AMF community in rice roots were affected by rice cultivation systems (the system of rice intensification [SRI] and the conventional rice cultivation system [CS]), and by compost application during growth stages. Rice plants harvested from SRI-managed plots exhibited considerably higher total biomass, root dry weight, and seed fill than those obtained from conventionally managed plots. Our findings revealed that all AMF sequences observed from CS plots belonged (only) to the genus Glomus, colonizing in rice roots grown under this type of cultivation, while rice roots sown in SRI showed sequences belonging to both Glomus and Acaulospora. The AMF community was compared between the different cultivation types (CS and SRI) and compost applications by principle component analysis. In all rice growth stages, AMF assemblages of CS management were not separated from those of SRI management. The distribution of AMF community composition based on T-RFLP data showed that the AMF community structure was different among four cultivation systems, and there was a gradual increase of Shannon-Weaver indices of diversity (H′) of the AMF community under SRI during growth stages. The results of this research indicated that rice grown in SRI-managed plots had more diverse AMF communities than those grown in CS plots. PMID:23719585

Evidence of root zone hypoxia in Brassica rapa L. grown in microgravity.

PubMed

Stout, S C; Porterfield, D M; Briarty, L G; Kuang, A; Musgrave, M E

2001-03-01

A series of experiments was conducted aboard the U.S. space shuttle and the Mir space station to evaluate microgravity-induced root zone hypoxia in rapid-cycling Brassica (Brassica rapa L.), using both root and foliar indicators of low-oxygen stress to the root zone. Root systems from two groups of plants 15 and 30 d after planting, grown in a phenolic foam nutrient delivery system on the shuttle (STS-87), were harvested and fixed for microscopy or frozen for enzyme assays immediately postflight or following a ground-based control. Activities of fermentative enzymes were measured as indicators of root zone hypoxia and metabolism. Following 16 d of microgravity, ADH (alcohol dehydrogenase) activity was increased in the spaceflight roots 47% and 475% in the 15-d-old and 30-d-old plants, respectively, relative to the ground control. Cytochemical localization showed ADH activity in only the root tips of the space-grown plants. Shoots from plants that were grown from seed in flight in a particulate medium on the Mir station were harvested at 13 d after planting and quick-frozen and stored in flight in a gaseous nitrogen freezer or chemically fixed in flight for subsequent microscopy. When compared to material from a high-fidelity ground control, concentrations of shoot sucrose and total soluble carbohydrate were significantly greater in the spaceflight treatment according to enzymatic carbohydrate analysis. Stereological analysis of micrographs of sections from leaf and cotyledon tissue fixed in flight and compared with ground controls indicated no changes in the volume of protoplast, cell wall, and intercellular space in parenchyma cells. Within the protoplasm, the volume occupied by starch was threefold higher in the spaceflight than in the ground control, with a concomitant decrease in vacuolar volume in the spaceflight treatment. Both induction of fermentative enzyme activity in roots and accumulation of carbohydrates in foliage have been repeatedly shown to occur in response to root zone oxygen deprivation. These results indicate that root zone hypoxia is a persistent challenge in spaceflight plant growth experiments and may be caused by microgravity-induced changes in fluid and gas distribution.

Evidence of root zone hypoxia in Brassica rapa L. grown in microgravity

NASA Technical Reports Server (NTRS)

Stout, S. C.; Porterfield, D. M.; Briarty, L. G.; Kuang, A.; Musgrave, M. E.

2001-01-01

A series of experiments was conducted aboard the U.S. space shuttle and the Mir space station to evaluate microgravity-induced root zone hypoxia in rapid-cycling Brassica (Brassica rapa L.), using both root and foliar indicators of low-oxygen stress to the root zone. Root systems from two groups of plants 15 and 30 d after planting, grown in a phenolic foam nutrient delivery system on the shuttle (STS-87), were harvested and fixed for microscopy or frozen for enzyme assays immediately postflight or following a ground-based control. Activities of fermentative enzymes were measured as indicators of root zone hypoxia and metabolism. Following 16 d of microgravity, ADH (alcohol dehydrogenase) activity was increased in the spaceflight roots 47% and 475% in the 15-d-old and 30-d-old plants, respectively, relative to the ground control. Cytochemical localization showed ADH activity in only the root tips of the space-grown plants. Shoots from plants that were grown from seed in flight in a particulate medium on the Mir station were harvested at 13 d after planting and quick-frozen and stored in flight in a gaseous nitrogen freezer or chemically fixed in flight for subsequent microscopy. When compared to material from a high-fidelity ground control, concentrations of shoot sucrose and total soluble carbohydrate were significantly greater in the spaceflight treatment according to enzymatic carbohydrate analysis. Stereological analysis of micrographs of sections from leaf and cotyledon tissue fixed in flight and compared with ground controls indicated no changes in the volume of protoplast, cell wall, and intercellular space in parenchyma cells. Within the protoplasm, the volume occupied by starch was threefold higher in the spaceflight than in the ground control, with a concomitant decrease in vacuolar volume in the spaceflight treatment. Both induction of fermentative enzyme activity in roots and accumulation of carbohydrates in foliage have been repeatedly shown to occur in response to root zone oxygen deprivation. These results indicate that root zone hypoxia is a persistent challenge in spaceflight plant growth experiments and may be caused by microgravity-induced changes in fluid and gas distribution.

RhizoTubes as a new tool for high throughput imaging of plant root development and architecture: test, comparison with pot grown plants and validation.

PubMed

Jeudy, Christian; Adrian, Marielle; Baussard, Christophe; Bernard, Céline; Bernaud, Eric; Bourion, Virginie; Busset, Hughes; Cabrera-Bosquet, Llorenç; Cointault, Frédéric; Han, Simeng; Lamboeuf, Mickael; Moreau, Delphine; Pivato, Barbara; Prudent, Marion; Trouvelot, Sophie; Truong, Hoai Nam; Vernoud, Vanessa; Voisin, Anne-Sophie; Wipf, Daniel; Salon, Christophe

2016-01-01

In order to maintain high yields while saving water and preserving non-renewable resources and thus limiting the use of chemical fertilizer, it is crucial to select plants with more efficient root systems. This could be achieved through an optimization of both root architecture and root uptake ability and/or through the improvement of positive plant interactions with microorganisms in the rhizosphere. The development of devices suitable for high-throughput phenotyping of root structures remains a major bottleneck. Rhizotrons suitable for plant growth in controlled conditions and non-invasive image acquisition of plant shoot and root systems (RhizoTubes) are described. These RhizoTubes allow growing one to six plants simultaneously, having a maximum height of 1.1 m, up to 8 weeks, depending on plant species. Both shoot and root compartment can be imaged automatically and non-destructively throughout the experiment thanks to an imaging cabin (RhizoCab). RhizoCab contains robots and imaging equipment for obtaining high-resolution pictures of plant roots. Using this versatile experimental setup, we illustrate how some morphometric root traits can be determined for various species including model (Medicago truncatula), crops (Pisum sativum, Brassica napus, Vitis vinifera, Triticum aestivum) and weed (Vulpia myuros) species grown under non-limiting conditions or submitted to various abiotic and biotic constraints. The measurement of the root phenotypic traits using this system was compared to that obtained using "classic" growth conditions in pots. This integrated system, to include 1200 Rhizotubes, will allow high-throughput phenotyping of plant shoots and roots under various abiotic and biotic environmental conditions. Our system allows an easy visualization or extraction of roots and measurement of root traits for high-throughput or kinetic analyses. The utility of this system for studying root system architecture will greatly facilitate the identification of genetic and environmental determinants of key root traits involved in crop responses to stresses, including interactions with soil microorganisms.

Some karyological observations on plants grown in space

NASA Technical Reports Server (NTRS)

Krikorian, A. D.; Oconnor, S. A.

1982-01-01

Experiments were conducted to assess whether cell division in a plant root would be affected by prolonged exposure to microgravity. Root materials from sunflower, oat, and mung bean plants grown on STS-2 and STS-3 were utilized for the experiments. It is found that all oat, sunflower, and mung seedlings showed a reduced number of cells in division as they went through their first cell division cycle on earth when compared to their ground controls. A significant number of oat, mung, and sunflower plantlets exhibited random root orientation and the lack of strictly orthotropic growth of their shoot systems in the flight samples. In addition, it is found that the mung roots were apparently least affected in terms of their cytology despite the fact that their roots were often randomly oriented.

Host Status of Five Weed Species and Their Effects on Pratylenchus zeae Infestation of Maize.

PubMed

Jordaan, E M; De Waele, D

1988-10-01

The host suitability of five of the most common weed species occurring in maize (Zea mays L.) fields in South Africa to Pratylenchus zeae was tested. Based on the number of nematodes per root unit, mealie crotalaria (Crotalaria sphaerocarpa) was a good host; goose grass (Eleusine indica), common pigweed (Amaranthus hybridus), and thorn apple (Datura stramonium) were moderate hosts; and khaki weed (Tagetes minuta) was a poor host. Only the root residues of khaki weed suppressed the P. zeae infestation of subsequently grown maize. When goose grass, khaki weed, and mealie crotalaria were grown in association with maize in soil infested with P. zeae, goose grass and khaki weed severely suppressed maize root development; this resulted in a low number of nematodes per maize root system and a high number of nematodes per maize root unit. Mealie crotalaria did not restrict maize root growth and did not affect nematode densities per maize root system or maize root unit. Special attention should be given to the control of mealie crotalaria, which is a good host for P. zeae, and goose grass, which, in addition to its ability to compete with maize, is also a suitable host for P. zeae.

Host Status of Five Weed Species and Their Effects on Pratylenchus zeae Infestation of Maize

PubMed Central

Jordaan, Elizabeth M.; De Waele, D.

1988-01-01

The host suitability of five of the most common weed species occurring in maize (Zea mays L.) fields in South Africa to Pratylenchus zeae was tested. Based on the number of nematodes per root unit, mealie crotalaria (Crotalaria sphaerocarpa) was a good host; goose grass (Eleusine indica), common pigweed (Amaranthus hybridus), and thorn apple (Datura stramonium) were moderate hosts; and khaki weed (Tagetes minuta) was a poor host. Only the root residues of khaki weed suppressed the P. zeae infestation of subsequently grown maize. When goose grass, khaki weed, and mealie crotalaria were grown in association with maize in soil infested with P. zeae, goose grass and khaki weed severely suppressed maize root development; this resulted in a low number of nematodes per maize root system and a high number of nematodes per maize root unit. Mealie crotalaria did not restrict maize root growth and did not affect nematode densities per maize root system or maize root unit. Special attention should be given to the control of mealie crotalaria, which is a good host for P. zeae, and goose grass, which, in addition to its ability to compete with maize, is also a suitable host for P. zeae. PMID:19290263

Root-shoot interaction in the greening of wheat seedlings grown under red light

NASA Technical Reports Server (NTRS)

Tripathy, B. C.; Brown, C. S.

1995-01-01

Wheat seedlings grown with roots exposed to constant red light (300-500 micromoles m-2 s-1) did not accumulate chlorophyll in the leaves. In contrast, seedlings grown with their roots shielded from light accumulated chlorophylls. Chlorophyll biosynthesis could be induced in red-light-grown chlorophyll-deficient yellow plants by either reducing the red-light intensity at the root surface to 100 micromoles m-1 s-1 or supplementing with 6% blue light. The inhibition of chlorophyll biosynthesis was due to impairment of the Mg-chelatase enzyme working at the origin of the Mg-tetrapyrrole pathway. The root-perceived photomorphogenic inhibition of shoot greening demonstrates root-shoot interaction in the greening process.

Relationships between root diameter, root length and root branching along lateral roots in adult, field-grown maize

PubMed Central

Wu, Qian; Pagès, Loïc; Wu, Jie

2016-01-01

Background and Aims Root diameter, especially apical diameter, plays an important role in root development and function. The variation in diameter between roots, and along roots, affects root structure and thus the root system’s overall foraging performance. However, the effect of diameter variation on root elongation, branching and topological connections has not been examined systematically in a population of high-order roots, nor along the roots, especially for mature plants grown in the field. Methods A method combining both excavation and analysis was applied to extract and quantify root architectural traits of adult, field-grown maize plants. The relationships between root diameter and other root architectural characteristics are analysed for two maize cultivars. Key Results The basal diameter of the lateral roots (orders 1–3) was highly variable. Basal diameter was partly determined by the diameter of the bearing segment. Basal diameter defined a potential root length, but the lengths of most roots fell far short of this. This was explained partly by differences in the pattern of diameter change along roots. Diameter tended to decrease along most roots, with the steepness of the gradient of decrease depending on basal diameter. The longest roots were those that maintained (or sometimes increased) their diameters during elongation. The branching density (cm–1) of laterals was also determined by the diameter of the bearing segment. However, the location of this bearing segment along the mother root was also involved – intermediate positions were associated with higher densities of laterals. Conclusions The method used here allows us to obtain very detailed records of the geometry and topology of a complex root system. Basal diameter and the pattern of diameter change along a root were associated with its final length. These relationships are especially useful in simulations of root elongation and branching in source–sink models. PMID:26744490

Bottles to trees: Plastic beverage bottles as an alternative nursery growing container for reforestation in developing countries.

PubMed

Khurram, Safiullah; Burney, Owen T; Morrissey, Robert C; Jacobs, Douglass F

2017-01-01

Reforestation is needed globally to help restore degraded sites, combat desertification, protect watersheds, and provide forest products. This involves planting forest tree seedlings grown in local nurseries, but technologies to produce quality seedlings are lacking in developing countries. Modern nursery containers used to propagate seedlings have internal-surface barriers (ribs or ridges) or side-slits to prevent root spiraling. These are cost prohibitive or unavailable in developing countries and so polybags (plastic bags) are more commonly used, despite their tendency to produce seedlings with deformed root systems that have less potential to establish on field sites. Discarded plastic bottles, which are readily available worldwide, may be a feasible alternative for seedling propagation. We conducted two experiments to assess the potential of repurposed plastic beverage bottles to grow quality trees: 1) Container Comparison-to evaluate Arizona walnut (Juglans major [Toor.] Heller) and Afghan pine (Pinus eldarica Medw.) seedling root and shoot development in two plastic bottle types compared to modern nursery containers and polybags, and 2) Bottle Modification-to examine the effects of root spiraling prevention techniques (side-slits, internal-ridges, and control) and container opacity (green, black, and clear) on Afghan pine seedling morphological attributes. Nursery growth and first-year seedling field performance were evaluated for both experiments. In experiment one, seedlings of both species had fewer spiraled roots in bottle containers compared to polybags. Arizona walnut had more fibrous root systems in polybags, while Afghan pine root system fibrosity was greatest in bottle containers. First-year field performance of both species was not affected by container type. In experiment two, less spiraled roots occurred in containers with air-slits and interior-ridges compared to the control. The effects of container opacity on seedling morphology were inconsistent. Root spiral prevention and opacity had no influence on Afghan pine one-year survival, field height and diameter, with the exception of opacity for height growth, whereby seedlings grown in green containers were taller than those grown in black containers, but seedlings grown in clear containers were similar to both. Our results provide the first evidence that plastic bottle containers may provide an effective alternative for production of high quality seedlings, which may benefit agroforestry, reforestation, restoration, and conservation programs in developing countries.

Bottles to trees: Plastic beverage bottles as an alternative nursery growing container for reforestation in developing countries

PubMed Central

Khurram, Safiullah; Burney, Owen T.; Morrissey, Robert C.

2017-01-01

Reforestation is needed globally to help restore degraded sites, combat desertification, protect watersheds, and provide forest products. This involves planting forest tree seedlings grown in local nurseries, but technologies to produce quality seedlings are lacking in developing countries. Modern nursery containers used to propagate seedlings have internal-surface barriers (ribs or ridges) or side-slits to prevent root spiraling. These are cost prohibitive or unavailable in developing countries and so polybags (plastic bags) are more commonly used, despite their tendency to produce seedlings with deformed root systems that have less potential to establish on field sites. Discarded plastic bottles, which are readily available worldwide, may be a feasible alternative for seedling propagation. We conducted two experiments to assess the potential of repurposed plastic beverage bottles to grow quality trees: 1) Container Comparison–to evaluate Arizona walnut (Juglans major [Toor.] Heller) and Afghan pine (Pinus eldarica Medw.) seedling root and shoot development in two plastic bottle types compared to modern nursery containers and polybags, and 2) Bottle Modification–to examine the effects of root spiraling prevention techniques (side-slits, internal-ridges, and control) and container opacity (green, black, and clear) on Afghan pine seedling morphological attributes. Nursery growth and first-year seedling field performance were evaluated for both experiments. In experiment one, seedlings of both species had fewer spiraled roots in bottle containers compared to polybags. Arizona walnut had more fibrous root systems in polybags, while Afghan pine root system fibrosity was greatest in bottle containers. First-year field performance of both species was not affected by container type. In experiment two, less spiraled roots occurred in containers with air-slits and interior-ridges compared to the control. The effects of container opacity on seedling morphology were inconsistent. Root spiral prevention and opacity had no influence on Afghan pine one-year survival, field height and diameter, with the exception of opacity for height growth, whereby seedlings grown in green containers were taller than those grown in black containers, but seedlings grown in clear containers were similar to both. Our results provide the first evidence that plastic bottle containers may provide an effective alternative for production of high quality seedlings, which may benefit agroforestry, reforestation, restoration, and conservation programs in developing countries. PMID:28562684

Effects of zinc toxicity on sugar beet (Beta vulgaris L.) plants grown in hydroponics.

PubMed

Sagardoy, R; Morales, F; López-Millán, A-F; Abadía, A; Abadía, J

2009-05-01

The effects of high Zn concentration were investigated in sugar beet (Beta vulgaris L.) plants grown in a controlled environment in hydroponics. High concentrations of Zn sulphate in the nutrient solution (50, 100 and 300 microm) decreased root and shoot fresh and dry mass, and increased root/shoot ratios, when compared to control conditions (1.2 microm Zn). Plants grown with excess Zn had inward-rolled leaf edges and a damaged and brownish root system, with short lateral roots. High Zn decreased N, Mg, K and Mn concentrations in all plant parts, whereas P and Ca concentrations increased, but only in shoots. Leaves of plants treated with 50 and 100 microm Zn developed symptoms of Fe deficiency, including decreases in Fe, chlorophyll and carotenoid concentrations, increases in carotenoid/chlorophyll and chlorophyll a/b ratios and de-epoxidation of violaxanthin cycle pigments. Plants grown with 300 microm Zn had decreased photosystem II efficiency and further growth decreases but did not have leaf Fe deficiency symptoms. Leaf Zn concentrations of plants grown with excess Zn were high but fairly constant (230-260 microg.g(-1) dry weight), whereas total Zn uptake per plant decreased markedly with high Zn supply. These data indicate that sugar beet could be a good model to investigate Zn homeostasis mechanisms in plants, but is not an efficient species for Zn phytoremediation.

Wheat Response to Differences In Water and Nutritional Status Between Zeoponic and Hydroponic Growth Systems

NASA Technical Reports Server (NTRS)

Steinberg, Susan L.; Ming, Douglas W.; Henderson, Keith E.; Carrier, Chris; Gruener, John E.; Barta, Dan J.; Henninger, Don L.

1999-01-01

Hydroponic culture has traditionally been used for controlled environment life support systems (CELSS) because the optimal environment for roots supports high growth rates. Recent developments in zeoponic substrate and microporous tube irrigation (ZPT) also offer high control of the root environment. This study compared the effect of differences in water and nutrient status of ZPT or hydroponic culture on growth and yield of wheat (Triticum aestivum L., CV 'USU-Apogee'). In a side-by-side test in a controlled environment, wheat was grown in ZPT and recirculating hydroponics to maturity. Water use by plants grown in both culture systems peaked at 15-20 L per square meters per d up to day 40, after which it declined more rapidly for plants grown in ZPT culture due to earlier senescence of leaves. No consistent differences were noted in water status between plants grown in the two culture systems. Although yield was similar, harvest index was 28% lower for plants grown in ZPT versus hydroponic culture. Sterile green tillers made up 12% and 0% of the biomass of plants grown in ZPT and hydroponic culture, respectively. Differences in biomass partitioning were attributed primarily to NH4 -N nutrition of plants grown in ZPT as compared with NO3-N in hydroponic nutrient solution. It was likely that NH4-N induced Ca deficiency produced excess tillering and lower harvest index for plants grown in ZPT culture. These results suggest that further refinements in zeoponic substrate would make ZPT culture a viable alternative for achieving high productivity in a CELSS.

Wheat response to differences in water and nutritional status between zeoponic and hydroponic growth systems

NASA Technical Reports Server (NTRS)

Steinberg, S. L.; Ming, D. W.; Henderson, K. E.; Carrier, C.; Gruener, J. E.; Barta, D. J.; Henninger, D. L.

2000-01-01

Hydroponic culture has traditionally been used for controlled environment life support systems (CELSS) because the optimal environment for roots supports high growth rates. Recent developments in zeoponic substrate and microporous tube irrigation (ZPT) also offer high control of the root environment. This study compared the effect of differences in water and nutrient status of ZPT or hydroponic culture on growth and yield of wheat (Triticum aestivum L. cv. USU-Apogee). In a side-by-side test in a controlled environment, wheat was grown in ZPT and recirculating hydroponics to maturity. Water use by plants grown in both culture systems peaked at 15 to 20 L m-2 d-1 up to Day 40, after which it declined more rapidly for plants grown in ZPT culture due to earlier senescence of leaves. No consistent differences in water status were noted between plants grown in the two culture systems. Although yield was similar, harvest index was 28% lower for plants grown in ZPT than in hydroponic culture. Sterile green tillers made up 12 and 0% of the biomass of plants grown in ZPT and hydroponic culture, respectively. Differences in biomass partitioning were attributed primarily to NH4-N nutrition of plants grown in ZPT compared with NO3-N in hydroponic nutrient solution. It is probable that NH4-N-induced Ca deficiency produced excess tillering and lower harvest index for plants grown in ZPT culture. These results suggest that further refinements in zeoponic substrate would make ZPT culture a viable alternative for achieving high productivity in a CELSS.

Distribution of glucosinolates and sulphur-rich cells in roots of field-grown canola (Brassica napus).

PubMed

McCully, Margaret E; Miller, Celia; Sprague, Susan J; Huang, Cheng X; Kirkegaard, John A

2008-01-01

To investigate the role played by the distribution pattern of glucosinolates (GSLs) in root systems in the release of biocides to the rhizosphere, GSLs have been localized, for the first time, to specific regions and cells in field-grown roots. GSL concentrations in separated tissues of canola (Brassica napus) were determined by chemical analysis, and cell-specific concentrations by extrapolation from sulphur concentrations obtained by quantitative cryo-analytical scanning electron microscopy (SEM). In roots with secondary growth, GSL concentrations in the outer secondary tissues were up to 5x those of the inner core. The highest GSL concentrations (from sulphur measurements) were in two cell layers just under the outermost periderm layer, with up to 100x published concentrations for whole roots. Primary tissues had negligible GSL. Release and renewal of the peripheral GSLs is probably a normal developmental process as secondary thickening continues and surface cells senesce, accounting for published observations that intact roots release GSLs and their biocide hydrolosates to the rhizosphere. Absence of myrosin idioblasts close to the root surface suggests that GSLs released developmentally are hydrolysed by myrosinase in the rhizosphere, ensuring a continuous localized source of biotoxic hydrolysates which can deter soil-borne pests, and influence microbial populations associated with long-lived components of the root system.

Prevention of Cold Damage to Container-Grown Longleaf Pine Roots

Treesearch

Richard W. Tinus; Mary Anne Sword; James P. Barnett

2002-01-01

When longleaf pine (Pinus palustris Mill.) seedlings are container-grown in open fields, their roots may be exposed to damaging, cold temperatures. Major losses in some nurseries have occurred. Between November 1996 and February 1997, we measured the cold hardiness of container-grown longleaf pine roots by measuring electrolyte leakage (a) of...

Barley root hair growth and morphology in soil, sand, and water solution media and relationship with nickel toxicity.

PubMed

Lin, Yanqing; Allen, Herbert E; Di Toro, Dominic M

2016-08-01

Barley, Hordeum vulgare (Doyce), was grown in the 3 media of soil, hydroponic sand solution (sand), and hydroponic water solution (water) culture at the same environmental conditions for 4 d. Barley roots were scanned, and root morphology was analyzed. Plants grown in the 3 media had different root morphology and nickel (Ni) toxicity response. Root elongations and total root lengths followed the sequence soil > sand > water. Plants grown in water culture were more sensitive to Ni toxicity and had greater root hair length than those from soil and sand cultures, which increased root surface area. The unit root surface area as root surface area per centimeter of length of root followed the sequence water > sand > soil and was found to be related with root elongation. Including the unit root surface area, the difference in root elongation and 50% effective concentration were diminished, and percentage of root elongations can be improved with a root mean square error approximately 10% for plants grown in different media. Because the unit root surface area of plants in sand culture is closer to that in soil culture, the sand culture method, not water culture, is recommended for toxicity parameter estimation. Environ Toxicol Chem 2016;35:2125-2133. © 2016 SETAC. © 2016 SETAC.

Identification of Fungal Colonies on Ground Control and Flight Veggie Plant Pillows

NASA Technical Reports Server (NTRS)

Scotten, Jessica E.; Hummerick, Mary E.; Khodadad, Christina L.; Spencer, Lashelle E.; Massa, Gioia D.

2017-01-01

The Veggie system focuses on growing fresh produce that can be harvested and consumed by astronauts. The microbial colonies in each Veggie experiment are evaluated to determine the safety level of the produce and then differences between flight and ground samples. The identifications of the microbial species can detail risks or benefits to astronaut and plant health. Each Veggie ground or flight experiment includes six plants grown from seeds that are glued into wicks in Teflon pillows filled with clay arcillite and fertilizer. Fungal colonies were isolated from seed wicks, growth media, and lettuce (cv. 'Outredgeous') roots grown in VEG-01B pillows on ISS and in corresponding ground control pillows grown in controlled growth chambers. The colonies were sorted by morphology and identified using MicroSeq(TM) 500 16s rDNA Bacterial Identification System and BIOLOG GEN III MicroPlate(TM). Health risks for each fungal identification were then assessed using literature sources. The goal was to identify all the colonies isolated from flight and ground control VEG-01B plants, roots, and rooting medium and compare the resulting identifications.

Effect of CO_2 levels on nutrient content of lettuce and radish

NASA Astrophysics Data System (ADS)

McKeehen, J. D.; Smart, D. J.; Mackowiak, C. L.; Wheeler, R. M.; Nielsen, S. S.

Atmospheric carbon-dioxide enrichment is known to affect the yield of lettuce and radish grown in controlled environments, but little is known about CO_2 enrichment effects on the chemical composition of lettuce and radish. These crops are useful model systems for a Controlled Ecological Life-Support System (CELSS), largely because of their relatively short production cycles. Lettuce (Lactuca sativa L.) cultivar `Waldmann's Green' and radish (Raphanus sativus L.) cultivar `Giant White Globe' were grown both in the field and in controlled environments, where hydroponic nutrient solution, light, and temperature were regulated, and where CO_2 levels were controlled at 400, 1000, 5000, or 10,000 ppm. Plants were harvested at maturity, dried, and analyzed for proximate composition (protein, fat, ash, and carbohydrate), total nitrogen (N), nitrate N, free sugars, starch, total dietary fiber, and minerals. Total N, protein N, nonprotein N (NPN), and nitrate N generally increased for radish roots and lettuce leaves when grown under growth chamber conditions compared to field conditions. The nitrate-N level of lettuce leaves, as a percentage of total NPN, decreased with increasing levels of CO_2 enrichment. The ash content of radish roots and of radish and lettuce leaves decreased with increasing levels of CO_2 enrichment. The levels of certain minerals differed between field- and chamber-grown materials, including changes in the calcium (Ca) and phosphorus (P) contents of radish roots and lettuce leaves, resulting in reduced Ca/P ratio for chamber-grown materials. The free-sugar contents were similar between the field and chamber-grown lettuce leaves, but total dietary fiber content was much higher in the field-grown plant material. The starch content of growth-chamber lettuce increased with CO_2 level.

A digital photography and analysis system for estimation of root and shoot development in rice weed suppression studies in the field

USDA-ARS?s Scientific Manuscript database

Rice germplasm with an inherent ability to suppress weeds can potentially improve the economics and sustainability of weed control in rice. We devised a simple, rapid, and inexpensive digital imaging system to quantify several shoot and root growth characteristics in field-grown rice plants that ha...

Superior Root Hair Formation Confers Root Efficiency in Some, But Not All, Rice Genotypes upon P Deficiency.

PubMed

Nestler, Josefine; Wissuwa, Matthias

2016-01-01

Root hairs are a low-cost way to extend root surface area (RSA), water and nutrient acquisition. This study investigated to what extend variation exists for root hair formation in rice in dependence of genotype, phosphorus (P) supply, growth medium, and root type. In general, genotypic variation was found for three root hair properties: root hair length, density, and longevity. In low P nutrient solution more than twofold genotypic difference was detected for root hair length while only onefold variation was found in low P soil. These differences were mostly due to the ability of some genotypes to increase root hair length in response to P deficiency. In addition, we were able to show that a higher proportion of root hairs remain viable even in mature, field-grown plants under low P conditions. All investigated root hair parameters exhibited high correlations across root types which were always higher in the low P conditions compared to the high P controls. Therefore we hypothesize that a low P response leads to a systemic signal in the entire root system. The genotype DJ123 consistently had the longest root hairs under low P conditions and we estimated that, across the field-grown root system, root hairs increased the total RSA by 31% in this genotype. This would explain why DJ123 is considered to be very root efficient in P uptake and suggests that DJ123 should be utilized as a donor in breeding for enhanced P uptake. Surprisingly, another root and P efficient genotype seemed not to rely on root hair growth upon P deficiency and therefore must contain different methods of low P adaptation. Genotypic ranking of root hair properties did change substantially with growth condition highlighting the need to phenotype plants in soil-based conditions or at least to validate results obtained in solution-based growth conditions.

Variation in Virus Symptom Development and Root Architecture Attributes at the Onset of Storage Root Initiation in ‘Beauregard’ Sweetpotato Plants Grown with or without Nitrogen

PubMed Central

Villordon, Arthur Q.; Clark, Christopher A.

2014-01-01

It has been shown that virus infections, often symptomless, significantly limit sweetpotato productivity, especially in regions characterized by low input agricultural systems. In sweetpotatoes, the successful emergence and development of lateral roots (LRs), the main determinant of root architecture, determines the competency of adventitious roots to undergo storage root initiation. This study aimed to investigate the effect of some plant viruses on root architecture attributes during the onset of storage root initiation in ‘Beauregard’ sweetpotatoes that were grown with or without the presence of nitrogen. In two replicate experiments, virus-tested plants consistently failed to show visible symptoms at 20 days regardless of nitrogen treatment. In both experiments, the severity of symptom development among infected plants ranged from 25 to 118% when compared to the controls (virus tested plants grown in the presence of nitrogen). The presence of a complex of viruses (Sweet potato feathery mottle virus, Sweet potato virus G, Sweet potato virus C, and Sweet potato virus 2) was associated with 51% reduction in adventitious root number among plants grown without nitrogen. The effect of virus treatments on first order LR development depended on the presence or absence of nitrogen. In the presence of nitrogen, only plants infected with Sweet potato chlorotic stunt virus showed reductions in first order LR length, number, and density, which were decreased by 33%, 12%, and 11%, respectively, when compared to the controls. In the absence of nitrogen, virus tested and infected plants manifested significant reductions for all first order LR attributes. These results provide evidence that virus infection directly influences sweetpotato yield potential by reducing both the number of adventitious roots and LR development. These findings provide a framework for understanding how virus infection reduces sweetpotato yield and could lead to the development of novel strategies to mitigate virus effects on sweetpotato productivity. PMID:25243579

An image processing and analysis tool for identifying and analysing complex plant root systems in 3D soil using non-destructive analysis: Root1.

PubMed

Flavel, Richard J; Guppy, Chris N; Rabbi, Sheikh M R; Young, Iain M

2017-01-01

The objective of this study was to develop a flexible and free image processing and analysis solution, based on the Public Domain ImageJ platform, for the segmentation and analysis of complex biological plant root systems in soil from x-ray tomography 3D images. Contrasting root architectures from wheat, barley and chickpea root systems were grown in soil and scanned using a high resolution micro-tomography system. A macro (Root1) was developed that reliably identified with good to high accuracy complex root systems (10% overestimation for chickpea, 1% underestimation for wheat, 8% underestimation for barley) and provided analysis of root length and angle. In-built flexibility allowed the user interaction to (a) amend any aspect of the macro to account for specific user preferences, and (b) take account of computational limitations of the platform. The platform is free, flexible and accurate in analysing root system metrics.

A Pipeline for 3D Digital Optical Phenotyping Plant Root System Architecture

NASA Astrophysics Data System (ADS)

Davis, T. W.; Shaw, N. M.; Schneider, D. J.; Shaff, J. E.; Larson, B. G.; Craft, E. J.; Liu, Z.; Kochian, L. V.; Piñeros, M. A.

2017-12-01

This work presents a new pipeline for digital optical phenotyping the root system architecture of agricultural crops. The pipeline begins with a 3D root-system imaging apparatus for hydroponically grown crop lines of interest. The apparatus acts as a self-containing dark room, which includes an imaging tank, motorized rotating bearing and digital camera. The pipeline continues with the Plant Root Imaging and Data Acquisition (PRIDA) software, which is responsible for image capturing and storage. Once root images have been captured, image post-processing is performed using the Plant Root Imaging Analysis (PRIA) command-line tool, which extracts root pixels from color images. Following the pre-processing binarization of digital root images, 3D trait characterization is performed using the next-generation RootReader3D software. RootReader3D measures global root system architecture traits, such as total root system volume and length, total number of roots, and maximum rooting depth and width. While designed to work together, the four stages of the phenotyping pipeline are modular and stand-alone, which provides flexibility and adaptability for various research endeavors.

Rhizophagus irregularis as an elicitor of rosmarinic acid and antioxidant production by transformed roots of Ocimum basilicum in an in vitro co-culture system.

PubMed

Srivastava, Shivani; Conlan, Xavier A; Cahill, David M; Adholeya, Alok

2016-11-01

Arbuscular mycorrhiza is a symbiotic association formed between plant roots and soil borne fungi that alter and at times improve the production of secondary metabolites. Detailed information is available on mycorrhizal development and its influence on plants grown under various edapho-climatic conditions, however, very little is known about their influence on transformed roots that are rich reserves of secondary metabolites. This raises the question of how mycorrhizal colonization progresses in transformed roots grown in vitro and whether the mycorrhizal fungus presence influences the production of secondary metabolites. To fully understand mycorrhizal ontogenesis and its effect on root morphology, root biomass, total phenolics, rosmarinic acid, caffeic acid and antioxidant production under in vitro conditions, a co-culture was developed between three Agrobacterium rhizogenes-derived, elite-transformed root lines of Ocimum basilicum and Rhizophagus irregularis. We found that mycorrhizal ontogenesis in transformed roots was similar to mycorrhizal roots obtained from an in planta system. Mycorrhizal establishment was also found to be transformed root line-specific. Colonization of transformed roots increased the concentration of rosmarinic acid, caffeic acid and antioxidant production while no effect was observed on root morphological traits and biomass. Enhancement of total phenolics and rosmarinic acid in the three mycorrhizal transformed root lines was found to be transformed root line-specific and age dependent. We reveal the potential of R. irregularis as a biotic elicitor in vitro and propose its incorporation into commercial in vitro secondary metabolite production via transformed roots.

Root exudation and root development of lettuce (Lactuca sativa L. cv. Tizian) as affected by different soils

PubMed Central

Neumann, G.; Bott, S.; Ohler, M. A.; Mock, H.-P.; Lippmann, R.; Grosch, R.; Smalla, K.

2014-01-01

Development and activity of plant roots exhibit high adaptive variability. Although it is well-documented, that physicochemical soil properties can strongly influence root morphology and root exudation, particularly under field conditions, a comparative assessment is complicated by the impact of additional factors, such as climate and cropping history. To overcome these limitations, in this study, field soils originating from an unique experimental plot system with three different soil types, which were stored at the same field site for 10 years and exposed to the same agricultural management practice, were used for an investigation on effects of soil type on root development and root exudation. Lettuce (Lactuca sativa L. cv. Tizian) was grown as a model plant under controlled environmental conditions in a minirhizotrone system equipped with root observation windows (rhizoboxes). Root exudates were collected by placing sorption filters onto the root surface followed by subsequent extraction and GC-MS profiling of the trapped compounds. Surprisingly, even in absence of external stress factors with known impact on root exudation, such as pH extremes, water and nutrient limitations/toxicities or soil structure effects (use of sieved soils), root growth characteristics (root length, fine root development) as well as profiles of root exudates were strongly influenced by the soil type used for plant cultivation. The results coincided well with differences in rhizosphere bacterial communities, detected in field-grown lettuce plants cultivated on the same soils (Schreiter et al., this issue). The findings suggest that the observed differences may be the result of plant interactions with the soil-specific microbiomes. PMID:24478764

Root exudation and root development of lettuce (Lactuca sativa L. cv. Tizian) as affected by different soils.

PubMed

Neumann, G; Bott, S; Ohler, M A; Mock, H-P; Lippmann, R; Grosch, R; Smalla, K

2014-01-01

Development and activity of plant roots exhibit high adaptive variability. Although it is well-documented, that physicochemical soil properties can strongly influence root morphology and root exudation, particularly under field conditions, a comparative assessment is complicated by the impact of additional factors, such as climate and cropping history. To overcome these limitations, in this study, field soils originating from an unique experimental plot system with three different soil types, which were stored at the same field site for 10 years and exposed to the same agricultural management practice, were used for an investigation on effects of soil type on root development and root exudation. Lettuce (Lactuca sativa L. cv. Tizian) was grown as a model plant under controlled environmental conditions in a minirhizotrone system equipped with root observation windows (rhizoboxes). Root exudates were collected by placing sorption filters onto the root surface followed by subsequent extraction and GC-MS profiling of the trapped compounds. Surprisingly, even in absence of external stress factors with known impact on root exudation, such as pH extremes, water and nutrient limitations/toxicities or soil structure effects (use of sieved soils), root growth characteristics (root length, fine root development) as well as profiles of root exudates were strongly influenced by the soil type used for plant cultivation. The results coincided well with differences in rhizosphere bacterial communities, detected in field-grown lettuce plants cultivated on the same soils (Schreiter et al., this issue). The findings suggest that the observed differences may be the result of plant interactions with the soil-specific microbiomes.

Live biospeckle laser imaging of root tissues.

PubMed

Braga, Roberto A; Dupuy, L; Pasqual, M; Cardoso, R R

2009-06-01

Live imaging is now a central component for the study of plant developmental processes. Currently, most techniques are extremely constraining: they rely on the marking of specific cellular structures which generally apply to model species because they require genetic transformations. The biospeckle laser (BSL) system was evaluated as an instrument to measure biological activity in plant tissues. The system allows collecting biospeckle patterns from roots which are grown in gels. Laser illumination has been optimized to obtain the images without undesirable specular reflections from the glass tube. Data on two different plant species were obtained and the ability of three different methods to analyze the biospeckle patterns are presented. The results showed that the biospeckle could provide quantitative indicators of the molecular activity from roots which are grown in gel substrate in tissue culture. We also presented a particular experimental configuration and the optimal approach to analyze the images. This may serve as a basis to further works on live BSL in order to study root development.

Untangling the effects of root age and tissue nitrogen on root respiration in Populus tremuloides at different nitrogen supply

PubMed Central

Ceccon, Christian; Tagliavini, Massimo; Schmitt, Armin Otto; Eissenstat, David M.

2016-01-01

Root respiration is a major contributor to terrestrial carbon flux. Many studies have shown root respiration to increase with an increase in root tissue nitrogen (N) concentration across species and study sites. Studies have also shown that both root respiration and root N concentration typically decrease with root age. The effects of added N may directly increase respiration of existing roots or may affect respiration by shifting the age structure of a root population by stimulating growth. To the best of our knowledge, no study has ever examined the effect of added N as a function of root age on root respiration. In this study, root respiration of 13-year-old Populus tremuloides Michx. trees grown in the field and 1-year-old P. tremuloides seedlings grown in containers was analyzed for the relative influence of root age and root N concentration independent of root age on root respiration. Field roots were first tracked using root windows and then sampled at known age. Nitrogen was either applied or not to small patches beneath the windows. In a pot experiment, each plant was grown with its root system split between two separate pots and N was applied at three different levels, either at the same or at different rates between pots. Root N concentration ranged between 1.4 and 1.7% in the field experiment and 1.8 and 2.6% in the seedling experiment. We found that addition of N increased root N concentration of only older roots in the field but of roots of all ages in the potted seedlings. In both experiments, the age-dependent decline in root respiration was largely consistent, and could be explained by a negative power function. Respiration decreased ∼50% by 3 weeks of age. Although root age was the dominant factor affecting respiration in both experiments, in the field experiment, root N also contributed to root respiration independent of root age. These results add further insight into respiratory responses of roots to N addition and mechanisms underlying the tissue N–respiration relationship. PMID:27095257

Free Radical Scavenging Activity and Comparative Metabolic Profiling of In Vitro Cultured and Field Grown Withania somnifera Roots

PubMed Central

Senthil, Kalaiselvi; Thirugnanasambantham, Pankajavalli; Oh, Taek Joo; Kim, So Hyun; Choi, Hyung Kyoon

2015-01-01

Free radical scavenging activity (FRSA), total phenolic content (TPC), and total flavonoid content (TFC) of in vitro cultured and field grown Withania somnifera (Ashwagandha) roots were investigated. Withanolides analysis and comprehensive metabolic profiling between 100% methanol extracts of in vitro and field grown root tissues was performed using high performance thin layer chromatography (HPTLC) and gas chromatography-mass spectrometry (GC-MS), respectively. Significantly higher levels of FRSA, TPC, and TFC were observed in in-vitro cultured roots compared with field grown samples. In addition, 30 day-cultured in vitro root samples (1MIR) exhibited a significantly higher FRSA (IC50 81.01 μg/mL), TPC (118.91 mg GAE/g), and TFC (32.68 mg CE/g) compared with those in 45 day-cultured samples (1.5MIR). Total of 29 metabolites were identified in in vitro cultured and field grown roots by GC-MS analysis. The metabolites included alcohols, organic acids, purine, pyrimidine, sugars, and putrescine. Vanillic acid was only observed in the in vitro cultured root samples, and higher level of the vanillic acid was observed in 1MIR when compared to 1.5MIR. Therefore, it is suggested that 1MIR might serve as an alternative to field grown roots for the development of medicinal and functional food products. PMID:25874568

Root Traits, Nodulation and Root Distribution in Soil for Five Wild Lentil Species and Lens culinaris (Medik.) Grown under Well-Watered Conditions.

PubMed

Gorim, Linda Y; Vandenberg, Albert

2017-01-01

The efficient use of resources such as water and nutrients by plants is increasingly important as the world population food demand continues to grow. With the increased production of lentil in the temperate zones of North America, improvement in yield needs to be maintained. The use of wild lentil genotypes as sources of genetic diversity for introgression into cultivated lentil is an important breeding strategy, but little is known about their root systems. We evaluated the root systems of five wild lentil species and Lens culinaris under fully watered conditions. Plants were grown in 60 cm tubes containing equal volumes of soil collected from the reconstructed A, B, and C horizons. Significant differences were observed for root traits and fine root distribution between and within species and the proportion of root biomass partitioned into each soil layer was unique for each genotype. We also observed variability in nodule number and nodule shape within and between genotypes. Some genotypes more efficiently used water for either biomass or seed production. The allocation of resources to seed production also varied between genotypes. These observations could have impact on the design of future lentil breeding in the context of strategies for managing changes in rainfall amount and distribution for lentil production ecosystems.

Evaluation of coffee genotypes for root-knot nematode resistance

USDA-ARS?s Scientific Manuscript database

Meloidogyne konaensis causes severe damage to the root systems of Coffea arabica cv. Typica ‘Guatemala’ grown in Kona, Hawaii. Farmers currently employ grafting of the nematode tolerant C. liberica var. dewevrei ‘Fukunaga’ to C. arabica cv. Typica scions. Greenhouse experiments confirmed C. liberi...

Ammonium-induced architectural and anatomical changes with altered suberin and lignin levels significantly change water and solute permeabilities of rice (Oryza sativa L.) roots.

PubMed

Ranathunge, Kosala; Schreiber, Lukas; Bi, Yong-Mei; Rothstein, Steven J

2016-01-01

Non-optimal ammonium levels significantly alter root architecture, anatomy and root permeabilities for water and nutrient ions. Higher ammonium levels induced strong apoplastic barriers whereas it was opposite for lower levels. Application of nitrogen fertilizer increases crop productivity. However, non-optimal applications can have negative effects on plant growth and development. In this study, we investigated how different levels of ammonium (NH4 (+)) [low (30 or 100 μM) or optimum (300 μM) or high (1000 or 3000 μM)] affect physio-chemical properties of 1-month-old, hydroponically grown rice roots. Different NH4 (+) treatments markedly altered the root architecture and anatomy. Plants grown in low NH4 (+) had the longest roots with a weak deposition of suberised and lignified apoplastic barriers, and it was opposite for plants grown in high NH4 (+). The relative expression levels of selected suberin and lignin biosynthesis candidate genes, determined using qRT-PCR, were lowest in the roots from low NH4 (+), whereas, they were highest for those grown in high NH4 (+). This was reflected by the suberin and lignin contents, and was significantly lower in roots from low NH4 (+) resulting in greater hydraulic conductivity (Lp r) and solute permeability (P sr) than roots from optimum NH4 (+). In contrast, roots grown at high NH4 (+) had markedly greater suberin and lignin contents, which were reflected by strong barriers. These barriers significantly decreased the P sr of roots but failed to reduce the Lp r below those of roots grown in optimum NH4 (+), which can be explained in terms of the physical properties of the molecules used and the size of pores in the apoplast. It is concluded that, in rice, non-optimal NH4 (+) levels differentially affected root properties including Lp r and P sr to successfully adapt to the changing root environment.

Cytological and ultrastructural studies on root tissues

NASA Technical Reports Server (NTRS)

Slocum, R. D.; Gaynor, J. J.; Galston, A. W.

1984-01-01

The anatomy and fine structure of roots from oat and mung bean seedlings, grown under microgravity conditions for 8 days aboard the Space Shuttle, was examined and compared to that of roots from ground control plants grown under similar conditions. Roots from both sets of oat seedlings exhibited characteristic monocotyledonous tissue organization and normal ultrastructural features, except for cortex cell mitochondria, which exhibited a 'swollen' morphology. Various stages of cell division were observed in the meristematic tissues of oat roots. Ground control and flight-grown mung bean roots also showed normal tissue organization, but root cap cells in the flight-grown roots were collapsed and degraded in appearance, especially at the cap periphery. At the ultrastructural level, these cells exhibited a loss of organelle integrity and a highly-condensed cytoplasm. This latter observation perhaps suggests a differing tissue sensitivity for the two species to growth conditions employed in space flight. The basis for abnormal root cap cell development is not understood, but the loss of these putative gravity-sensing cells holds potential significance for long term plant growth orientation during space flight.

Plastic responses of native plant root systems to the presence of an invasive annual grass.

PubMed

Phillips, Allison J; Leger, Elizabeth A

2015-01-01

• The ability to respond to environmental change via phenotypic plasticity may be important for plants experiencing disturbances such as climate change and plant invasion. Responding to belowground competition through root plasticity may allow native plants to persist in highly invaded systems such as the cold deserts of the Intermountain West, USA.• We investigated whether Poa secunda, a native bunchgrass, could alter root morphology in response to nutrient availability and the presence of a competitive annual grass. Seeds from 20 families were grown with high and low nutrients and harvested after 50 d, and seeds from 48 families, grown with and without Bromus tectorum, were harvested after ∼2 or 6 mo. We measured total biomass, root mass fraction, specific root length (SRL), root tips, allocation to roots of varying diameter, and plasticity in allocation.• Plants had many parallel responses to low nutrients and competition, including increased root tip production, a trait associated with tolerance to reduced resources, though families differed in almost every trait and correlations among trait changes varied among experiments, indicating flexibility in plant responses. Seedlings actively increased SRL and fine root allocation under competition, while older seedlings also increased coarse root allocation, a trait associated with increased tolerance, and increased root mass fraction.• The high degree of genetic variation for root plasticity within natural populations could aid in the long-term persistence of P. secunda because phenotypic plasticity may allow native species to persist in invaded and fluctuating resource environments. © 2015 Botanical Society of America, Inc.

A Soil-Plate Based Pipeline for Assessing Cereal Root Growth in Response to Polyethylene Glycol (PEG)-Induced Water Deficit Stress

PubMed Central

Nelson, Sven K.; Oliver, Melvin J.

2017-01-01

Drought is a serious problem that causes losses in crop-yield every year, but the mechanisms underlying how roots respond to water deficit are difficult to study under controlled conditions. Methods for assaying root elongation and architecture, especially for seedlings, are commonly achieved on artificial media, such as agar, moistened filter paper, or in hydroponic systems. However, it has been demonstrated that measuring root characteristics under such conditions does not accurately mimic what is observed when plants are grown in soil. Morphological changes in root behavior occur because of differences in solute diffusion, mechanical impedance, exposure to light (in some designs), and gas exchange of roots grown under these conditions. To address such deficiencies, we developed a quantitative method for assaying seedling root lengths and germination in soil using a plate-based approach with wheat as a model crop. We also further developed the method to include defined water deficits stress levels using the osmotic properties of polyethylene glycol (PEG). Seeds were sown into soil-filled vertical plates and grown in the dark. Root length measurements were collected using digital photography through the transparent lid under green lighting to avoid effects of white light exposure on growth. Photographs were analyzed using the cross-platform ImageJ plugin, SmartRoot, which can detect root edges and partially automate root detection for extraction of lengths. This allowed for quick measurements and straightforward and accurate assessments of non-linear roots. Other measurements, such as root width or angle, can also be collected by this method. An R function was developed to collect exported root length data, process and reformat the data, and output plots depicting root/shoot growth dynamics. For water deficit experiments, seedlings were transplanted side-by-side into well-watered plates and plates containing PEG solutions to simulate precise water deficits. PMID:28785272

A Soil-Plate Based Pipeline for Assessing Cereal Root Growth in Response to Polyethylene Glycol (PEG)-Induced Water Deficit Stress.

PubMed

Nelson, Sven K; Oliver, Melvin J

2017-01-01

Drought is a serious problem that causes losses in crop-yield every year, but the mechanisms underlying how roots respond to water deficit are difficult to study under controlled conditions. Methods for assaying root elongation and architecture, especially for seedlings, are commonly achieved on artificial media, such as agar, moistened filter paper, or in hydroponic systems. However, it has been demonstrated that measuring root characteristics under such conditions does not accurately mimic what is observed when plants are grown in soil. Morphological changes in root behavior occur because of differences in solute diffusion, mechanical impedance, exposure to light (in some designs), and gas exchange of roots grown under these conditions. To address such deficiencies, we developed a quantitative method for assaying seedling root lengths and germination in soil using a plate-based approach with wheat as a model crop. We also further developed the method to include defined water deficits stress levels using the osmotic properties of polyethylene glycol (PEG). Seeds were sown into soil-filled vertical plates and grown in the dark. Root length measurements were collected using digital photography through the transparent lid under green lighting to avoid effects of white light exposure on growth. Photographs were analyzed using the cross-platform ImageJ plugin, SmartRoot, which can detect root edges and partially automate root detection for extraction of lengths. This allowed for quick measurements and straightforward and accurate assessments of non-linear roots. Other measurements, such as root width or angle, can also be collected by this method. An R function was developed to collect exported root length data, process and reformat the data, and output plots depicting root/shoot growth dynamics. For water deficit experiments, seedlings were transplanted side-by-side into well-watered plates and plates containing PEG solutions to simulate precise water deficits.

An Evaluation of Root Phytochemicals Derived from Althea officinalis (Marshmallow) and Astragalus membranaceus as Potential Natural Components of UV Protecting Dermatological Formulations

PubMed Central

Curnow, Alison; Owen, Sara J.

2016-01-01

As lifetime exposure to ultraviolet (UV) radiation has risen, the deleterious effects have also become more apparent. Numerous sunscreen and skincare products have therefore been developed to help reduce the occurrence of sunburn, photoageing, and skin carcinogenesis. This has stimulated research into identifying new natural sources of effective skin protecting compounds. Alkaline single-cell gel electrophoresis (comet assay) was employed to assess aqueous extracts derived from soil or hydroponically glasshouse-grown roots of Althea officinalis (Marshmallow) and Astragalus membranaceus, compared with commercial, field-grown roots. Hydroponically grown root extracts from both plant species were found to significantly reduce UVA-induced DNA damage in cultured human lung and skin fibroblasts, although initial Astragalus experimentation detected some genotoxic effects, indicating that Althea root extracts may be better suited as potential constituents of dermatological formulations. Glasshouse-grown soil and hydroponic Althea root extracts afforded lung fibroblasts with statistically significant protection against UVA irradiation for a greater period of time than the commercial field-grown roots. No significant reduction in DNA damage was observed when total ultraviolet irradiation (including UVB) was employed (data not shown), indicating that the extracted phytochemicals predominantly protected against indirect UVA-induced oxidative stress. Althea phytochemical root extracts may therefore be useful components in dermatological formulations. PMID:26953144

An Evaluation of Root Phytochemicals Derived from Althea officinalis (Marshmallow) and Astragalus membranaceus as Potential Natural Components of UV Protecting Dermatological Formulations.

PubMed

Curnow, Alison; Owen, Sara J

2016-01-01

As lifetime exposure to ultraviolet (UV) radiation has risen, the deleterious effects have also become more apparent. Numerous sunscreen and skincare products have therefore been developed to help reduce the occurrence of sunburn, photoageing, and skin carcinogenesis. This has stimulated research into identifying new natural sources of effective skin protecting compounds. Alkaline single-cell gel electrophoresis (comet assay) was employed to assess aqueous extracts derived from soil or hydroponically glasshouse-grown roots of Althea officinalis (Marshmallow) and Astragalus membranaceus, compared with commercial, field-grown roots. Hydroponically grown root extracts from both plant species were found to significantly reduce UVA-induced DNA damage in cultured human lung and skin fibroblasts, although initial Astragalus experimentation detected some genotoxic effects, indicating that Althea root extracts may be better suited as potential constituents of dermatological formulations. Glasshouse-grown soil and hydroponic Althea root extracts afforded lung fibroblasts with statistically significant protection against UVA irradiation for a greater period of time than the commercial field-grown roots. No significant reduction in DNA damage was observed when total ultraviolet irradiation (including UVB) was employed (data not shown), indicating that the extracted phytochemicals predominantly protected against indirect UVA-induced oxidative stress. Althea phytochemical root extracts may therefore be useful components in dermatological formulations.

Increased soil phosphorus availability induced by faba bean root exudation stimulates root growth and phosphorus uptake in neighbouring maize.

PubMed

Zhang, Deshan; Zhang, Chaochun; Tang, Xiaoyan; Li, Haigang; Zhang, Fusuo; Rengel, Zed; Whalley, William R; Davies, William J; Shen, Jianbo

2016-01-01

Root growth is influenced by soil nutrients and neighbouring plants, but how these two drivers affect root interactions and regulate plant growth dynamics is poorly understood. Here, interactions between the roots of maize (Zea mays) and faba bean (Vicia faba) are characterized. Maize was grown alone (maize) or with maize (maize/maize) or faba bean (maize/faba bean) as competitors under five levels of phosphorus (P) supply, and with homogeneous or heterogeneous P distribution. Maize had longer root length and greater shoot biomass and P content when grown with faba bean than with maize. At each P supply rate, faba bean had a smaller root system than maize but greater exudation of citrate and acid phosphatase, suggesting a greater capacity to mobilize P in the rhizosphere. Heterogeneous P availability enhanced the root-length density of maize but not faba bean. Maize root proliferation in the P-rich patches was associated with increased shoot P uptake. Increased P availability by localized P application or by the presence of faba bean exudation stimulated root morphological plasticity and increased shoot growth in maize in the maize/faba bean mixture, suggesting that root interactions of neighbouring plants can be modified by increased P availability. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

Effect of soil water content on spatial distribution of root exudates and mucilage in the rhizosphere

NASA Astrophysics Data System (ADS)

Holz, Maire; Zarebanadkouki, Mohsen; Kuzyakov, Yakov; Carminati, Andrea

2016-04-01

Water and nutrients are expected to become the major factors limiting food production. Plant roots employ various mechanisms to increase the access to these limited soil resources. Low molecular root exudates released into the rhizosphere increase nutrient availability, while mucilage improves water availability under low moisture conditions. However, studies on the spatial distribution and quantification of exudates in soil are scarce. Our aim was therefore to quantify and visualize root exudates and mucilage distribution around growing roots using neutron radiography and 14C imaging at different levels of water stress. Maize plants were grown in rhizotrons filled with a silty soil and were exposed to varying soil conditions, from optimal to dry. Mucilage distribution around the roots was estimated from the profiles of water content in the rhizosphere - note that mucilage increases the soil water content. The profiles of water content around different root types and root ages were measured with neutron radiography. Rhizosphere extension was approx. 0.7 mm and did not differ between wet and dry treatments. However, water content (i.e. mucilage concentration) in the rhizosphere of plants grown in dry soils was higher than for plants grown under optimal conditions. This effect was particularly pronounced near the tips of lateral roots. The higher water contents near the root are explained as the water retained by mucilage. 14C imaging of root after 14CO2 labeling of shoots (Pausch and Kuzyakov 2011) was used to estimate the distribution of all rhizodeposits. Two days after labelling, 14C distribution was measured using phosphor-imaging. To quantify 14C in the rhizosphere a calibration was carried out by adding given amounts of 14C-glucose to soil. Plants grown in wet soil transported a higher percentage of 14C to the roots (14Croot/14Cshoot), compared to plants grown under dry conditions (46 vs. 36 %). However, the percentage of 14C allocated from roots to rhizosphere (14Crhizosphere/14Croot) was double in plants grown under dry conditions (0.43 vs. 0.75 %). Plants grown in wet soils showed a faster root growth (1.4 cm d-1) compared to plants in dry soil (1 cm d-1). Compared to the results with neutron radiography, rhizosphere extension of 14C was generally higher and strongly depended on root type: it was 2 mm for main roots and 1 mm for lateral roots. This indicates that low molecular exudates diffuse further into the soil than mucilage. As for mucilage, concentration of 14C was higher in the rhizosphere of plants grown under dry conditions. This observation can be explained by: (a) higher allocation of 14C from roots to rhizosphere in dry soils, (b) a fast diffusion of exudates in wet soils, and (c) faster root growth in wet soils, which results in lower exudation per root length. In summary, the combination of neutron radiography and 14C imaging was successfully used to visualize and to quantify the distribution of mucilage and root exudates in the rhizosphere of plants grown in soil. The high concentration of root exudates in rhizosphere under dry conditions might be strategy of plants to increase their water and nutrient availability unfavorable conditions.

Mutualism in a Reduced Gravity Environment (MuRGE)

NASA Technical Reports Server (NTRS)

Haire, Timothy C.

2010-01-01

Mutualism in a Reduced Gravity Environment (MuRGE) is a ground research study to determine the feasibility of assessing fungi-plant (Piriformospora indica-Arabidopsis thaliana) interactions in microgravity. Seeds from the plant Arabiddospsis thaliana (At) will be grown in the presence of Piriformospora indica (Pi) an endophytic Sebacinacae family fungus. Pi is capable of colonizing the roots of a wide variety of plant species, including non-mycorrhizal hosts like At, and promoting plant growth similarly to AMF (arbusuclar mychorrizal fungi) unlike most AMF, Pi is not an obligate plant symbiont and can be grown in the absence of a host. In the presence of a suitable plant host, Pi can attach to and colonize root tips. Interaction visualization is accomplished with strong autofluorescence in the roots, followed by root colonization via fungal hyphae, and chlamydospore production. Increased root growth can be observed even before root colonization is detectable. In addition, Pi chlamydospores generated from axenic culture in microgravity will be used to inoculate roots of At grown in 1g to determine the effect of microgravity upon the inherent virulence or beneficial effects. Based on recent reports of increased virulence of S. typhimurium, P. aeruginosa, and S. Pneumoniae in reduced gravity, differences in microbial pathogenic responses and host plant systemic acquired resistance are expected. The focus of this project within MuRGE involved the development P. indica culture media evaluation and microscopy protocol development. High, clean spore harvest yields for the detection of fungi-plant interactions microscopically was the immediate goal of this experiment.

Root decisions.

PubMed

Hodge, Angela

2009-06-01

Root systems have recognizable developmental plans when grown in solution or agar; however, these plans often must be modified to cope with the prevailing conditions in the soil environment such as the avoidance of obstacles and the exploitation of nutrient-rich patches or water zones. The modular structure of roots enables them to respond to their environment, and roots are very adaptive at modifying growth throughout the root system to concentrate their efforts in the areas that are the most profitable. Roots also form associations with microorganisms as a strategy to enhance resource capture. However, while the responses of roots in nutrient patches are well-recognized, overall 'rules of response' and variation in strategy among plant species that can be applied in a number of different environments are still lacking. Finally, there is increasing evidence that root-root interactions are much more sophisticated than previously thought, and the evidence for roots to identify self from non-self roots will be briefly discussed.

Inositol 1,4,5-trisphosphate distribution in Lycopersicon esculentum Mill seedlings cultivated "in vitro" under different conditions.

PubMed

Placentini, M P; Ricci, D; Fraternale, D; Piatti, E; Manunta, A; Accorsi, A

1997-04-01

Measurements of inositol 1,4,5-trisphosphate (Ins1,4,5-P3) in cotyledons, epicotyls and roots of tomato seedlings grown "in vitro" either in the light or in the dark indicated that higher concentrations of this signal-transducing molecule are contained in hypogeous vs. epigeous tissues. The same was observed in induced cotyledon explants grown in the light in the presence of growth regulators. Data concerning phosphatidylinositol metabolism in seedling roots are also reported. Taken together, our results may be helpful in understanding the role of the polyphosphoinositide signal system in plants.

Untangling the effects of root age and tissue nitrogen on root respiration in Populus tremuloides at different nitrogen supply.

PubMed

Ceccon, Christian; Tagliavini, Massimo; Schmitt, Armin Otto; Eissenstat, David M

2016-05-01

Root respiration is a major contributor to terrestrial carbon flux. Many studies have shown root respiration to increase with an increase in root tissue nitrogen (N) concentration across species and study sites. Studies have also shown that both root respiration and root N concentration typically decrease with root age. The effects of added N may directly increase respiration of existing roots or may affect respiration by shifting the age structure of a root population by stimulating growth. To the best of our knowledge, no study has ever examined the effect of added N as a function of root age on root respiration. In this study, root respiration of 13-year-old Populus tremuloides Michx. trees grown in the field and 1-year-old P. tremuloides seedlings grown in containers was analyzed for the relative influence of root age and root N concentration independent of root age on root respiration. Field roots were first tracked using root windows and then sampled at known age. Nitrogen was either applied or not to small patches beneath the windows. In a pot experiment, each plant was grown with its root system split between two separate pots and N was applied at three different levels, either at the same or at different rates between pots. Root N concentration ranged between 1.4 and 1.7% in the field experiment and 1.8 and 2.6% in the seedling experiment. We found that addition of N increased root N concentration of only older roots in the field but of roots of all ages in the potted seedlings. In both experiments, the age-dependent decline in root respiration was largely consistent, and could be explained by a negative power function. Respiration decreased ∼50% by 3 weeks of age. Although root age was the dominant factor affecting respiration in both experiments, in the field experiment, root N also contributed to root respiration independent of root age. These results add further insight into respiratory responses of roots to N addition and mechanisms underlying the tissue N-respiration relationship. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Vesicular-arbuscular mycorrhizae of Easter lily in the northwestern United States.

PubMed

Ames, R N; Linderman, R G

1977-12-01

The vesicular-arbuscular (VA) mycorrhizal fungi of commercially grown Easter lily (Lilium longiflorum Thunb.) were studied. Soil and root samples were collected monthly from March through September 1975 from five fields in the coastal area of southern Oregon and northern California. Soil seivings were inoculated onto clover, onion, and lily to cause infections resulting in the production of many new mycorrhizal spores facilitating identification. Four VA mycorrhizal species were found: Acaulospora trappei, A. elegans, Glomus monosporus, and G. fasciculatus. All four VA species infected Easter lily, clover, and onion. Acaulospora trappei and G. fasciculatus were the most commonly isolated species from all five fields. Mycorrhizal infections in roots of field-grown lilies were sparse and presumably young in March and gradually increased in size and number until September when bulbs were harvested. Over 75% of each root system became infected with mycorrhizae in fields with all four fungal species, and those levels were reached by July. In fields with only two mycorrhizal species, usually 50% or less of each root system was infected, even by the end of the growing season.

Symptom development in response to combined infection of in vitro grown Lilium longiflorum with the root lesion nematode Pratylenchus penetrans and soilborne fungi collected from diseased roots of field-grown lilies

USDA-ARS?s Scientific Manuscript database

Eight fungal isolates (ELRF 1-8) were isolated from necrotic roots of Lilium longiflorum cv. Nellie White (Easter lily) grown in a field in the U.S. Pacific Northwest. The eight fungal isolates were identified by sequencing and molecular phylogenetic analyses based on their ITS rDNA region. Five iso...

Carboxylate metabolism in sugar beet plants grown with excess Zn.

PubMed

Sagardoy, R; Morales, F; Rellán-Álvarez, R; Abadía, A; Abadía, J; López-Millán, A F

2011-05-01

The effects of Zn excess on carboxylate metabolism were investigated in sugar beet (Beta vulgaris L.) plants grown hydroponically in a growth chamber. Root extracts of plants grown with 50 or 100μM Zn in the nutrient solution showed increases in several enzymatic activities related to organic acid metabolism, including citrate synthase and phosphoenolpyruvate carboxylase, when compared to activities in control root extracts. Root citric and malic acid concentrations increased in plants grown with 100μM Zn, but not in plants grown with 50μM Zn. In the xylem sap, plants grown with 50 and 100μM Zn showed increases in the concentrations of citrate and malate compared to the controls. Leaves of plants grown with 50 or 100μM Zn showed increases in the concentrations of citric and malic acid and in the activities of citrate synthase and fumarase. Leaf isocitrate dehydrogenase increased only in plants grown with 50μM Zn when compared to the controls. In plants grown with 300μM Zn, the only enzyme showing activity increases in root extracts was citrate synthase, whereas the activities of other enzymes decreased compared to the controls, and root citrate concentrations increased. In the 300μM Zn-grown plants, the xylem concentrations of citric and malic acids were higher than those of controls, whereas in leaf extracts the activity of fumarase increased markedly, and the leaf citric acid concentration was higher than in the controls. Based on our data, a metabolic model of the carboxylate metabolism in sugar beet plants grown under Zn excess is proposed. Copyright © 2010 Elsevier GmbH. All rights reserved.

Early field performance of Acacia koa seedlings grown under subirrigation and overhead irrigation

Treesearch

Anthony S. Davis; Jeremiah R. Pinto; Douglass F. Jacobs

2011-01-01

Koa (Acacia koa A. Gray [Fabaceae]) seedlings were grown with subirrigation and overhead irrigation systems in an effort to characterize post-nursery field performance. One year following outplanting, we found no differences in seedling height or survival, but root-collar diameter was significantly larger for subirrigated seedlings. This indicates that koa seedlings,...

A rapid, controlled-environment seedling root screen for wheat correlates well with rooting depths at vegetative, but not reproductive, stages at two field sites

PubMed Central

Watt, M.; Moosavi, S.; Cunningham, S. C.; Kirkegaard, J. A.; Rebetzke, G. J.; Richards, R. A.

2013-01-01

Background and Aims Root length and depth determine capture of water and nutrients by plants, and are targets for crop improvement. Here we assess a controlled-environment wheat seedling screen to determine speed, repeatability and relatedness to performance of young and adult plants in the field. Methods Recombinant inbred lines (RILs) and diverse genotypes were grown in rolled, moist germination paper in growth cabinets, and primary root number and length were measured when leaf 1 or 2 were fully expanded. For comparison, plants were grown in the field and root systems were harvested at the two-leaf stage with either a shovel or a soil core. From about the four-leaf stage, roots were extracted with a steel coring tube only, placed directly over the plant and pushed to the required depth with a hydraulic ram attached to a tractor. Key Results In growth cabinets, repeatability was greatest (r = 0·8, P < 0·01) when the paper was maintained moist and seed weight, pathogens and germination times were controlled. Scanned total root length (slow) was strongly correlated (r = 0·7, P < 0·01) with length of the two longest seminal axile roots measured with a ruler (fast), such that 100–200 genotypes were measured per day. Correlation to field-grown roots at two sites at two leaves was positive and significant within the RILs and cultivars (r = 0·6, P = 0·01), and at one of the two sites at the five-leaf stage within the RILs (r = 0·8, P = 0·05). Measurements made in the field with a shovel or extracted soil cores were fast (5 min per core) and had significant positive correlations to scanner measurements after root washing and cleaning (>2 h per core). Field measurements at two- and five-leaf stages did not correlate with root depth at flowering. Conclusions The seedling screen was fast, repeatable and reliable for selecting lines with greater total root length in the young vegetative phase in the field. Lack of significant correlation with reproductive stage root system depth at the field sites used in this study reflected factors not captured in the screen such as time, soil properties, climate variation and plant phenology. PMID:23821620

Hydrotropism in pea roots in a porous-tube water delivery system

NASA Technical Reports Server (NTRS)

Takahashi, H.; Brown, C. S.; Dreschel, T. W.; Scott, T. K.; Knott, W. M. (Principal Investigator)

1992-01-01

Orientation of root growth on earth and under microgravity conditions can possibly be controlled by hydrotropism--growth toward a moisture source in the absence of or reduced gravitropism. A porous-tube water delivery system being used for plant growth studies is appropriate for testing this hypothesis since roots can be grown aeroponically in this system. When the roots of the agravitropic mutant pea ageotropum (Pisum sativum L.) were placed vertically in air of 91% relative humidity and 2 to 3 mm from the water-saturated porous tube placed horizontally, the roots responded hydrotropically and grew in a continuous arch along the circular surface of the tube. By contrast, normal gravitropic roots of Alaska' pea initially showed a slight transient curvature toward the tube and then resumed vertical downward growth due to gravitropism. Thus, in microgravity, normal gravitropic roots could respond to a moisture gradient as strongly as the agravitropic roots used in this study. Hydrotropism should be considered a significant factor responsible for orientation of root growth in microgravity.

Thymol derivatives from hairy roots of Arnica montana.

PubMed

Weremczuk-Jezyna, I; Kisiel, W; Wysokińska, H

2006-09-01

Five known thymol derivatives were isolated from roots of Arnica montana transformed with Agrobacterium rhizogenes LBA 9402. The compounds were characterized by spectral methods. The pattern of thymol derivatives in light-grown hairy roots was slightly different from that in dark-grown ones. This is the first report on the presence of thymol derivatives in hairy roots of the plant.

Impact of elemental uptake in the root chemistry of wetland plants.

PubMed

Aryal, Rupak; Nirola, Ramkrishna; Beecham, Simon; Kamruzzaman, Mohammad

2016-09-01

Plants play a key role in the accumulation of metals in contaminated environment. Ephemeral plants, such as cyperus vaginatus, from the family Cyperaceae have been used in constructed wetlands to alter the biogeochemistry of waterlogged soils. High elemental content in wetlands often induces chemical changes in the root, stem and leaf of wetland plants. Elemental uptake and possible chemical changes in the roots of Cyperus vaginatus was investigated and compared with plants grown away from the wetland. Among the 9 heavy metals (Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd, and Pb) and metalloid (As) measured, with the exception of Mn, all metals had higher content in the plant roots grown within the wetland. This was followed by plants grown near to the wetland that receive stormwater occasionally and then plants grown far from the wetland. The 3-D fluorescence spectra record showed notable differences in the chemical composition of roots grown in the three locations. The spectra combined with parallel factor analysis showed three dominant fluorescence components. Comparison of the fluorescence signatures showed a continuum of spectral properties constrained by the degree of metal contamination.

Field and laboratory root growth and development of Lesquerella germplasm

USDA-ARS?s Scientific Manuscript database

Lesquerella roots have not been fully characterized as compared to other crop species. There is initial information gathered on root trait variation in young seedling grown in laboratory settings but studies to determine if the results can be extrapolated in field grown plants are lacking. We report...

DOE Office of Scientific and Technical Information (OSTI.GOV)

Patil, Swapnil M.; Chandanshive, Vishal V.; Rane, Niraj R.

In vitro grown untransformed adventitious roots (AR) culture of Ipomoea hederifolia and its endophytic fungus (EF) Cladosporium cladosporioides decolorized Navy Blue HE2R (NB-HE2R) at a concentration of 20 ppm up to 83.3 and 65%, respectively within 96 h. Whereas the AR-EF consortium decolorized the dye more efficiently and gave 97% removal within 36 h. Significant inductions in the enzyme activities of lignin peroxidase, tyrosinase and laccase were observed in roots, while enzymes like tyrosinase, laccase and riboflavin reductase activities were induced in EF. Metabolites of dye were analyzed using UV—vis spectroscopy, FTIR and gas chromatography-mass spectrometry. Possible metabolic pathways ofmore » NB-HE2R were proposed with AR, EF and AR-EF systems independently. Looking at the superior efficacy of AR-EF system, a rhizoreactor was developed for the treatment of NB-HE2R at a concentration of 1000 ppm. Control reactor systems with independently grown AR and EF gave 94 and 85% NB-HE2R removal, respectively within 36 h. The AR-EF rhizoreactor, however, gave 97% decolorization. The endophyte colonization additionally increased root and shoot lengths of candidate plants through mutualism. Combined bioreactor strategies can be effectively used for future eco-friendly remediation purposes. - Highlights: • Endophytic fungus on Ipomoea hederifolia promotes root growth and shoot development • Endophytic Cladosporium cladosporioides synergistically degrade Navy Blue-HE2R dye • Endophyte colonized I. hederifolia roots proved superior in dye decolorization • Dye stress and toxicity was efficiently dealt by root-endophyte consortium • Root-endophyte consortium can be used as a sustainable remediation strategy.« less

Root Growth Patterns and Morphometric Change Based on the Growth Media

NASA Astrophysics Data System (ADS)

Schultz, Eric R.; Paul, Anna-Lisa; Ferl, Robert J.

2016-12-01

Arabidopsis thaliana roots skew with minimal waving in the microgravity environment of the International Space Station. Root skewing and root waving have been studied on the ground as well as in spaceflight, but often using different media types. In this study, Arabidopsis seedlings were grown on nutrient media plates that were comprised of various gelling agents with varied hardness in order to better assess these media for spaceflight research experiments. ImageJ was used to quantify the root morphology of 8-dayold seedlings, while R was used to perform statistical analyses. Root growth was drastically different between Difco agar, agarose, and Phytagel. Additionally, root waving masked skewing in certain media. Regression analysis revealed overall patterns when organized by hardness but also revealed that differences in media type had more of an impact on root growth than hardness itself. Different arrangements of media around the root tip revealed that roots grown on the media surface were longer and had fewer waves per millimeter than roots grown embedded in media. The implications for spaceflight research are discussed.

SEMIPERMEABLE MEMBRANE SYSTEM FOR SUBJECTING PLANTS TO WATER STRESS

EPA Science Inventory

A system was evaluated for growing plants at reproducible levels of water stress. Beans (Phaseolus vulgaris L.) were grown in vermiculite, transferred to a semipermeable membrane system that encased the root vermiculate mass, and then placed into nutrient solutions to which vario...

Gravity-induced differentiations and deficiency in flower formation observed on Columbus experiment WAICO1

NASA Astrophysics Data System (ADS)

Scherer, Günther; Pietrzyk, Peter

The Arabidopsis Atpla-I-3 knockout mutant (gene nr. At1g61859) is deficient in gravitropism and phototropism indicating a defect in the auxin transport system. The mutant roots form higher numbers of root coils on 45° angle tilted agar. Root tip coils exhibit right-handed spiral pattern of the rhizodermis cells suggesting that torsion of rhizodermis cells could provide a driving force for asymmetrical growth and coiling. WAICO1 was designed to test whether the tendency to for coils by asymmetric tip growth may be provided by torsion of external rhizodermis cells or, alternatively, the asymmetric growth is driven by intrinsic forces in the root. Coil formation is often increased in root agravitropic mutants so that an increase of coils by lack of gravity -and thus absence of gravisensing -was the favoured working hypothesis. Two agar boxes each of wild type and mutant seedlings were grown inside of an outer growth container at 22.5° C in constant light and at a 45° angle tilted, in the 1G rotor and in the microgravity rotor. At first, the samples grown in microgravity could be retrieved from orbit as cooled (4° -8° C) material. They were investigated by microscopy and compared to photographs made in orbit of 1G and µG plants by astronaut. Plants first grown in 1G were retrieved much later (see below). Mutant and wt formed high numbers of coils in microgravity, whereas in 1G none were observed which is comparable to growth experiments on the ground. However, the mutant developed a lower percentage of spiral pattern in the rhizodermal cells despite an even higher number of coils as observed in the wt. The results show that asymmetrical growth of root tips is an intrinsic property and independent of forces that may be exerted by the rhizodermal pattern. Surprisingly, in both wild type and mutant a much higher number of lateral roots were found in µG-grown plants than in plants grown in the 1G-centrifuge after 12 d, suggesting that gravity suppresses lateral root formation. When mutants and wt only grown in the 1G centrifuge were compared the mutant leaves and cotyledons were smaller than in wt and hypocotyls were longer, but when the plants in µG for 12d were compared this difference was not found. Hence, gravity had an influence on leaf expansion and hypocotyl length in the mutant. The samples grown for 12d in 1G were kept in µG after 12d on due to a technical failure of the 1G centrifuge. They were retrieved about a year later. They had grown to full senescence and were preserved in a beautiful state as "straw". The observations on the root patterns by the astronaut photos at day 12 could be confirmed but plants had grown on and newer roots made coils just as the plants grown µG. Leaf sizes were different for wt and mutant. The most striking observation was that the mutants had developed small flower stems with a few flower buds but many flowers were incomplete, without the proper sepal or petal number or without gynaecium. The wild type plants had not developed any clear flower stem but only several malformed cell clumps shortly above the rosette. In ground laboratory experiments the mutants flower earlier which might explain why they developed flowers to some extent whereas the wt not at all. Microgravity might be a "stress" for flower formation. Taken together, several gravity-induced (or microgravity-induced) changes in differentiation occurred.

Survival of Potentially Pathogenic Human-Associated Bacteria in the Rhizosphere of Hydroponically Grown Wheat

NASA Technical Reports Server (NTRS)

Morales, Anabelle; Garland, Jay L.; Lim, Daniel V.

1996-01-01

Plants may serve as reservoirs for human-associated bacteria (H-AB) in long-term space missions containing bioregenerative life support systems. The current study examined the abilities of five human-associated potential pathogens, Pseudomonas aeruginosa, Pseudomonas cepacia, Staphylococcus aureus, Streptococcus pyogenes, and Escherichia coli, to colonize and grow in the rhizosphere of hydroponically grown wheat, a candidate crop for life support. All of these bacteria have been recovered from past NASA missions and present potential problems for future missions. The abilities of these organisms to adhere to the roots of axenic five-day-old wheat (Triticum aestivum L. cv. Yecora rojo) were evaluated by enumeration of the attached organisms after a one hour incubation of roots in a suspension (approximately 10(exp 8 cu/ml)) of the H-AB. Results showed that a greater percentage of P. aeruginosa cells adhered to the wheat roots than the other four H-AB. Similarly incubated seedlings were also grown under attempted axenic conditions for seven days to examine the potential of each organism to proliferate in the rhizosphere (root colonization capacity). P. cepacia and P. aeruginosa showed considerable growth. E. coli and S. aureus showed no significant growth, and S. pyogenes died off in the wheat rhizosphere. Studies examining the effects of competition on the survival of these microorganisms indicated that P. aeruginosa was the only organism that survived in the rhizosphere of hydroponically grown wheat in the presence of different levels of microbial competition.

Rhizo-lysimetry: facilities for the simultaneous study of root behaviour and resource use by agricultural crop and pasture systems

PubMed Central

2013-01-01

Background Rhizo-lysimeters offer unique advantages for the study of plants and their interactions with soils. In this paper, an existing facility at Charles Sturt University in Wagga Wagga Australia is described in detail and its potential to conduct both ecophysiological and ecohydrological research in the study of root interactions of agricultural crops and pastures is quantitatively assessed. This is of significance to future crop research efforts in southern Australia, in light of recent significant long-term drought events, as well as potential impacts of climate change as predicted for the region. The rhizo-lysimeter root research facility has recently been expanded to accommodate larger research projects over multiple years and cropping rotations. Results Lucerne, a widely-grown perennial pasture in southern Australia, developed an expansive root system to a depth of 0.9 m over a twelve month period. Its deeper roots particularly at 2.05 m continued to expand for the duration of the experiment. In succeeding experiments, canola, a commonly grown annual crop, developed a more extensive (approximately 300%) root system than wheat, but exhibited a slower rate of root elongation at rates of 7.47 x 10–3 m day–1 for canola and 1.04 x10–2 m day–1 for wheat. A time domain reflectometry (TDR) network was designed to accurately assess changes in soil water content, and could assess water content change to within 5% of the amount of water applied. Conclusions The rhizo-lysimetry system provided robust estimates of root growth and soil water change under conditions representative of a field setting. This is currently one of a very limited number of global research facilities able to perform experimentation under field conditions and is the largest root research experimental laboratory in the southern hemisphere. PMID:23363534

To what extent may changes in the root system architecture of Arabidopsis thaliana grown under contrasted homogenous nitrogen regimes be explained by changes in carbon supply? A modelling approach.

PubMed

Brun, François; Richard-Molard, Céline; Pagès, Loïc; Chelle, Michaël; Ney, Bertrand

2010-05-01

Root system architecture adapts to low nitrogen (N) nutrition. Some adaptations may be mediated by modifications of carbon (C) fluxes. The objective of this study was to test the hypothesis that changes in root system architecture under different N regimes may be accounted for by using simple hypotheses of C allocation within the root system of Arabidopsis thaliana. With that purpose, a model during vegetative growth was developed that predicted the main traits of root system architecture (total root length, lateral root number, and specific root length). Different experimental data sets crossing three C levels and two N homogenous nutrition levels were generated. Parameters were estimated from an experiment carried out under medium C and high N conditions. They were then checked under other CxN conditions. It was found that the model was able to simulate correctly C effects on root architecture in both high and low N nutrition conditions, with the same parameter values. It was concluded that C flux modifications explained the major part of root system adaptation to N supply, even if they were not sufficient to simulate some changes, such as specific root length.

Bioreactor with Ipomoea hederifolia adventitious roots and its endophyte Cladosporium cladosporioides for textile dye degradation.

PubMed

Patil, Swapnil M; Chandanshive, Vishal V; Rane, Niraj R; Khandare, Rahul V; Watharkar, Anuprita D; Govindwar, Sanjay P

2016-04-01

In vitro grown untransformed adventitious roots (AR) culture of Ipomoea hederifolia and its endophytic fungus (EF) Cladosporium cladosporioides decolorized Navy Blue HE2R (NB-HE2R) at a concentration of 20 ppm up to 83.3 and 65%, respectively within 96h. Whereas the AR-EF consortium decolorized the dye more efficiently and gave 97% removal within 36h. Significant inductions in the enzyme activities of lignin peroxidase, tyrosinase and laccase were observed in roots, while enzymes like tyrosinase, laccase and riboflavin reductase activities were induced in EF. Metabolites of dye were analyzed using UV-vis spectroscopy, FTIR and gas chromatography-mass spectrometry. Possible metabolic pathways of NB-HE2R were proposed with AR, EF and AR-EF systems independently. Looking at the superior efficacy of AR-EF system, a rhizoreactor was developed for the treatment of NB-HE2R at a concentration of 1000 ppm. Control reactor systems with independently grown AR and EF gave 94 and 85% NB-HE2R removal, respectively within 36h. The AR-EF rhizoreactor, however, gave 97% decolorization. The endophyte colonization additionally increased root and shoot lengths of candidate plants through mutualism. Combined bioreactor strategies can be effectively used for future eco-friendly remediation purposes. Copyright © 2016 Elsevier Inc. All rights reserved.

Growth and yield responses of field-grown sweetpotato to elevated carbon dioxide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Biswas, P.K.; Hileman, D.R.; Ghosh, P.P.

1996-09-01

Root crops are important in developing countries, where food supplies are frequently marginal. Increases in atmospheric CO{sub 2} usually lead to increases in plant growth and yield, but little is known about the response of root crops to CO{sub 2} enrichment under field conditions. This experiment was conducted to investigate the effects of CO{sub 2} enrichment on growth and yield of field-grown sweetpotato. Plants were grown in open-top chambers in the field at four CO{sub 2} levels ranging from 354 (ambient) to 665 {mu}mol mol{sup {minus}1} in two growing seasons. Shoot growth was not affected significantly by elevated CO{sub 2}.more » Yield of storage roots increased 46 and 75% at the highest CO{sub 2} level in the 2 yr. The yield enhancement occurred through increases in the number of storage roots in the second year. Storage-root/shoot ratios increased 44% and leaf nitrogen concentrations decreased by 24% at the highest CO{sub 2} level. A comparison of plants grown in the open field to plants grown in open-top chambers at ambient CO{sub 2} concentrations indicated that open-top chambers reduced shoot growth in the first year and storage-root yield in both years. These results are consistent with the majority of CO{sub 2}-enrichment studies done on pot-grown sweetpotato. 37 refs., 2 figs., 5 tabs.« less

The Effect of Plant Cultivar, Growth Media, Harvest Method and Post Harvest Treatment on the Microbiology of Edible Crops

NASA Technical Reports Server (NTRS)

Hummerick, Mary P.; Gates, Justin R.; Nguyen, Bao-Thang; Massa, Gioia D.; Wheeler, Raymond M.

2011-01-01

Systems for the growth of crops in closed environments are being developed and tested for potential use in space applications to provide a source of fresh food. Plant growth conditions, growth media composition and harvest methods can have an effect on the microbial population of the plant, and therefore should be considered along with the optimization of plant growth and harvest yields to ensure a safe and palatable food crop. This work examines the effect of plant cultivar, growth media, and harvest method on plant microbial populations. Twelve varieties of leafy greens and herbs were grown on a mixture of Fafard #2 and Arcillite in the pillow root containment system currently being considered for the VEGGIE plant growth unit developed by Orbitec. In addition, ,Sierra and Outredgeous lettuce varieties were grown in three different mixtures (Fafard #2, Ardllite, and Perlite/Vermiculite). The plants were analyzed for microbial density. Two harvest methods, "cut and come again" (CACA) and terminal harvest were also compared. In one set ofexpe'riments red leaf lettuce and mizuna were grown in pots in a Biomass Production System for education. Plants were harvested every two weeks by either method. Another set of experiments was performed using the rooting pillows to grow 5 varieties of leafy greens and cut harvesting at different intervals. Radishes were harvested and replanted at two-week intervals. Results indicate up to a 3 IOglO difference in microbial counts between some varieties of plants. Rooting medium resulted in an approximately 2 IOglO lower count in the lettuce grown in arscillite then those grown in the other mixtures. Harvest method and frequency had less impact on microbial counts only showing a significant increase in one variety of plant. Post harvest methods to decrease the bacterial counts on edible crops were investigated in these and other experiments. The effectiveness of PRO-SAN and UV-C radiation is compared.

Weed Growth and Efficacy of Pre-Applied Herbicides in Alternative Rooting Substrates Used in Container-Grown Nursery Crops

USDA-ARS?s Scientific Manuscript database

Container-grown nursery crops in the Southeastern United States are typically grown in a rooting substrate comprised primarily of the ground bark of pine trees. However pine bark is becoming less available and more costly due to changes in production and marketed practices within Southeastern pine f...

Production and early field performance of RPM® seedlings in Missouri floodplains

Treesearch

Daniel C. Dey; Wayne Lovelace; John M. Kabrick; Michael A. Gold

2004-01-01

A new nursery culture process has been developed to produce large container RPM? seedlings in an effort to improve the success in artificially regenerating hardwoods. Major features of the process include air root pruning of seedlings grown in a well aerated soil medium to encourage a dense, fibrous root system. Production has focused on native bottomland tree, shrub,...

Ontogeny of Daucus carota Infected with Meloidogyne hapla

PubMed Central

Slinger, L. A.; Bird, G. W.

1978-01-01

The ontogeny of carrots (Daucus carota cv. 'Spartan Premium') grown under greenhouse conditions in pots of organic soil infected with Meloidogyne hapla was influenced detrimentally as early as 4 days after seeding, as determined through analysis of plant surface area, dry weight, fresh weight, net assimilation rate, relative growth rate, and leaf-area ratio. Only 58% of the diseased carrots were suitable for fresh market, compared with 97% of those grown in nematode-free soil. Growth and development of the shoot system (height, surface area, dry weight, and fresh weight) were retarded by M. hapla as early as 12 days after seeding. During the first 12 days after seeding, root dry weight was greater for diseased plants than for controls. Root growth and development (surface area, dry weight, and fresh weight) associated with this nematode, however, were retarded as early as 16 days after seeding. M. hapla caused a delay in the occurrence of 2nd-, 4th-, and 5th-order roots, and an increase in the occurrence of 6th-order roots in infected plants. Parasitized plants had 44% fewer roots (primary through 6th-order) and 50% less total root length. PMID:19305837

Evaluation of instrumentation systems in reducing E. faecalis from root canals: TF adaptive and ProTaper next versus single file systems.

PubMed

Karataş, Ertuğrul; Gültekin, Esra; Arslan, Hakan; Kirici, Damla Özsu; Alsancak, Meltem; Topçu, Meltem Çolak

2015-03-01

To compare the effect of the TF Adaptive, ProTaper Next, OneShape, WaveOne, Reciproc, (SAF) on the reduction of E. faecalis in experimentally infected root canals. 70 human mandibular incisor teeth with straight roots and single root canals were selected for this experiment and the root canals of the selected teeth were infected with E. faecalis. After contamination, all the root canals were randomly divided into 7 groups: control, ProTaper Next, TF Adaptive, SAF, WaveOne, Reciproc, and OneShape. After the irrigation procedures, samples were taken from root canals with paper points and incubated in blood agar plates. The colonies grown on the blood agar were counted and interpreted as colony forming units per milliliter. Analysis of results showed that all instrumentation systems were more effective in reducing the number of bacteria than the control (P<.001). The ProTaper Next, TF Adaptive, WaveOne, Reciproc, and OneShape systems were significantly more effective than the SAF system in reducing E. faecalis within the root canals (P<.001). All instrumentation systems used in this study provided a significant reduction in bacterial populations.

Regulation of root development in Arabidopsis thaliana by phytohormone-secreting epiphytic methylobacteria.

PubMed

Klikno, Jana; Kutschera, Ulrich

2017-09-01

In numerous experimental studies, seedlings of the model dicot Arabidopsis thaliana have been raised on sterile mineral salt agar. However, under natural conditions, no plant has ever grown in an environment without bacteria. Here, we document that germ-free (gnotobiotic) seedlings, raised on mineral salt agar without sucrose, develop very short root hairs. In the presence of a soil extract that contains naturally occurring microbes, root hair elongation is promoted; this effect can be mimicked by the addition of methylobacteria to germ-free seedlings. Using five different bacterial species (Methylobacterium mesophilicum, Methylobacterium extorquens, Methylobacterium oryzae, Methylobacterium podarium, and Methylobacterium radiotolerans), we show that, over 9 days of seedling development in a light-dark cycle, root development (hair elongation, length of the primary root, branching patterns) is regulated by these epiphytic microbes that occur in the rhizosphere of field-grown plants. In a sterile liquid culture test system, auxin (IAA) inhibited root growth with little effect on hair elongation and significantly stimulated hypocotyl enlargement. Cytokinins (trans-zeatin, kinetin) and ethylene (application of the precursor ACC) likewise exerted an inhibitory effect on root growth but, in contrast to IAA, drastically stimulated root hair elongation. Methylobacteria are phytosymbionts that produce/secrete cytokinins. We conclude that, under real-world conditions (soil), the provision of these phytohormones by methylobacteria (and other epiphytic microbes) regulates root development during seedling establishment.

Grasses suppress shoot-borne roots to conserve water during drought

PubMed Central

Sebastian, Jose; Yee, Muh-Ching; Goudinho Viana, Willian; Rellán-Álvarez, Rubén; Feldman, Max; Priest, Henry D.; Trontin, Charlotte; Lee, Tak; Jiang, Hui; Mockler, Todd C.

2016-01-01

Many important crops are members of the Poaceae family, which develop root systems characterized by a high degree of root initiation from the belowground basal nodes of the shoot, termed the crown. Although this postembryonic shoot-borne root system represents the major conduit for water uptake, little is known about the effect of water availability on its development. Here we demonstrate that in the model C4 grass Setaria viridis, the crown locally senses water availability and suppresses postemergence crown root growth under a water deficit. This response was observed in field and growth room environments and in all grass species tested. Luminescence-based imaging of root systems grown in soil-like media revealed a shift in root growth from crown-derived to primary root-derived branches, suggesting that primary root-dominated architecture can be induced in S. viridis under certain stress conditions. Crown roots of Zea mays and Setaria italica, domesticated relatives of teosinte and S. viridis, respectively, show reduced sensitivity to water deficit, suggesting that this response might have been influenced by human selection. Enhanced water status of maize mutants lacking crown roots suggests that under a water deficit, stronger suppression of crown roots actually may benefit crop productivity. PMID:27422554

Next Generation Image-Based Phenotyping of Root System Architecture

NASA Astrophysics Data System (ADS)

Davis, T. W.; Shaw, N. M.; Cheng, H.; Larson, B. G.; Craft, E. J.; Shaff, J. E.; Schneider, D. J.; Piñeros, M. A.; Kochian, L. V.

2016-12-01

The development of the Plant Root Imaging and Data Acquisition (PRIDA) hardware/software system enables researchers to collect digital images, along with all the relevant experimental details, of a range of hydroponically grown agricultural crop roots for 2D and 3D trait analysis. Previous efforts of image-based root phenotyping focused on young cereals, such as rice; however, there is a growing need to measure both older and larger root systems, such as those of maize and sorghum, to improve our understanding of the underlying genetics that control favorable rooting traits for plant breeding programs to combat the agricultural risks presented by climate change. Therefore, a larger imaging apparatus has been prototyped for capturing 3D root architecture with an adaptive control system and innovative plant root growth media that retains three-dimensional root architectural features. New publicly available multi-platform software has been released with considerations for both high throughput (e.g., 3D imaging of a single root system in under ten minutes) and high portability (e.g., support for the Raspberry Pi computer). The software features unified data collection, management, exploration and preservation for continued trait and genetics analysis of root system architecture. The new system makes data acquisition efficient and includes features that address the needs of researchers and technicians, such as reduced imaging time, semi-automated camera calibration with uncertainty characterization, and safe storage of the critical experimental data.

Root morphology, hydraulic conductivity and plant water relations of high-yielding rice grown under aerobic conditions.

PubMed

Kato, Yoichiro; Okami, Midori

2011-09-01

Increasing physical water scarcity is a major constraint for irrigated rice (Oryza sativa) production. 'Aerobic rice culture' aims to maximize yield per unit water input by growing plants in aerobic soil without flooding or puddling. The objective was to determine (a) the effect of water management on root morphology and hydraulic conductance, and (b) their roles in plant-water relationships and stomatal conductance in aerobic culture. Root system development, stomatal conductance (g(s)) and leaf water potential (Ψ(leaf)) were monitored in a high-yielding rice cultivar ('Takanari') under flooded and aerobic conditions at two soil moisture levels [nearly saturated (> -10 kPa) and mildly dry (> -30 kPa)] over 2 years. In an ancillary pot experiment, whole-plant hydraulic conductivity (soil-leaf hydraulic conductance; K(pa)) was measured under flooded and aerobic conditions. Adventitious root emergence and lateral root proliferation were restricted even under nearly saturated conditions, resulting in a 72-85 % reduction in total root length under aerobic culture conditions. Because of their reduced rooting size, plants grown under aerobic conditions tended to have lower K(pa) than plants grown under flooded conditions. Ψ(leaf) was always significantly lower in aerobic culture than in flooded culture, while g(s) was unchanged when the soil moisture was at around field capacity. g(s) was inevitably reduced when the soil water potential at 20-cm depth reached -20 kPa. Unstable performance of rice in water-saving cultivations is often associated with reduction in Ψ(leaf). Ψ(leaf) may reduce even if K(pa) is not significantly changed, but the lower Ψ(leaf) would certainly occur in case K(pa) reduces as a result of lower water-uptake capacity under aerobic conditions. Rice performance in aerobic culture might be improved through genetic manipulation that promotes lateral root branching and rhizogenesis as well as deep rooting.

Absence of plant uptake and translocation of polybrominated biphenyls (PBBs).

PubMed

Chou, S F; Jacobs, L W; Penner, D; Tiedje, J M

1978-04-01

Studies of polybrominated biphenyl (PBB) uptake by plants have been conducted in hydroponic solutions and in greenhouse experiments with soil. Autoradiograms of corn and soybean seedlings grown in hydroponic solutions showed no translocation of 14C-PBB from 14C-PBB-treated solutions to plant tops or within the leaf from 14C-PBB-treated spots on the upper leaf surface. A significant portion of the 14C-PBB associated with the roots was removed when the roots were dipped in acetone. Three root crops (radishes, carrots, and onions) were grown in two soils, each treated with a mixture of FireMaster BP-6 (PBB) and 14C-PBB to achieve final concentrations of 100 ppm and 100 ppb. All roots showed more PBB when grown in the soil with the lower clay and organic matter content than they did when grown in the soil with more clay and organic matter. In the latter soil (clay loam) no PBB was detected in any roots from the 100 ppb treatment. More PBB was associated with roots of carrot than of radish or onion. Corn leaf whorls containing dust from a PBB contamination soil and washed radishes from a heavily contaminated garden showed no PBB.

Root system architecture: The invisible trait in container longleaf pine seedlings

Treesearch

Shi-Jean Susana Sung; R. Kasten Dumroese

2013-01-01

Longleaf pine (Pinus palustris Mill.) seedlings cultured in four cavity volumes (60 to 336 ml [3.7 to 20.5 cubic inches]), two root pruning treatments (with or without copper coating), and 3 nitrogen levels (low to high) were grown for 29 weeks before they were outplanted into an open area in central Louisiana. Twenty-two months after outplanting, 3 seedlings were...

Maize root culture as a model system for studying azoxystrobin biotransformation in plants.

PubMed

Gautam, Maheswor; Elhiti, Mohamed; Fomsgaard, Inge S

2018-03-01

Hairy roots induced by Agrobacterium rhizogenes are well established models to study the metabolism of xenobiotics in plants for phytoremediation purposes. However, the model requires special skills and resources for growing and is a time-consuming process. The roots induction process alters the genetic construct of a plant and is known to express genes that are normally absent from the non-transgenic plants. In this study, we propose and establish a non-transgenic maize root model to study xenobiotic metabolism in plants for phytoremediation purpose using azoxystrobin as a xenobiotic compound. Maize roots were grown aseptically in Murashige and Skoog medium for two weeks and were incubated in 100 μM azoxystrobin solution. Azoxystrobin was taken up by the roots to the highest concentration within 15 min of treatment and its phase I metabolites were also detected at the same time. Conjugated metabolites of azoxystrobin were detected and their identities were confirmed by enzymatic and mass spectrometric methods. Further, azoxystrobin metabolites identified in maize root culture were compared against azoxystrobin metabolites in azoxystrobin sprayed lettuce grown in green house. A very close similarity between metabolites identified in maize root culture and lettuce plant was obtained. The results from this study establish that non-transgenic maize roots can be used for xenobiotic metabolism studies instead of genetically transformed hairy roots due to the ease of growing and handling. Copyright © 2017 Elsevier Ltd. All rights reserved.

Modelling the root system architecture of Poaceae. Can we simulate integrated traits from morphological parameters of growth and branching?

PubMed

Pagès, Loïc; Picon-Cochard, Catherine

2014-10-01

Our objective was to calibrate a model of the root system architecture on several Poaceae species and to assess its value to simulate several 'integrated' traits measured at the root system level: specific root length (SRL), maximum root depth and root mass. We used the model ArchiSimple, made up of sub-models that represent and combine the basic developmental processes, and an experiment on 13 perennial grassland Poaceae species grown in 1.5-m-deep containers and sampled at two different dates after planting (80 and 120 d). Model parameters were estimated almost independently using small samples of the root systems taken at both dates. The relationships obtained for calibration validated the sub-models, and showed species effects on the parameter values. The simulations of integrated traits were relatively correct for SRL and were good for root depth and root mass at the two dates. We obtained some systematic discrepancies that were related to the slight decline of root growth in the last period of the experiment. Because the model allowed correct predictions on a large set of Poaceae species without global fitting, we consider that it is a suitable tool for linking root traits at different organisation levels. © 2014 INRA. New Phytologist © 2014 New Phytologist Trust.

A complete system for 3D reconstruction of roots for phenotypic analysis.

PubMed

Kumar, Pankaj; Cai, Jinhai; Miklavcic, Stanley J

2015-01-01

Here we present a complete system for 3D reconstruction of roots grown in a transparent gel medium or washed and suspended in water. The system is capable of being fully automated as it is self calibrating. The system starts with detection of root tips in root images from an image sequence generated by a turntable motion. Root tips are detected using the statistics of Zernike moments on image patches centred on high curvature points on root boundary and Bayes classification rule. The detected root tips are tracked in the image sequence using a multi-target tracking algorithm. Conics are fitted to the root tip trajectories using a novel ellipse fitting algorithm which weighs the data points by its eccentricity. The conics projected from the circular trajectory have a complex conjugate intersection which are image of the circular points. Circular points constraint the image of the absolute conics which are directly related to the internal parameters of the camera. The pose of the camera is computed from the image of the rotation axis and the horizon. The silhouettes of the roots and camera parameters are used to reconstruction the 3D voxel model of the roots. We show the results of real 3D reconstruction of roots which are detailed and realistic for phenotypic analysis.

Low phosphate alters lateral root setpoint angle and gravitropism.

PubMed

Bai, Hanwen; Murali, Bhavna; Barber, Kevin; Wolverton, Chris

2013-01-01

Lateral roots, responsible for water and nutrient uptake, maintain nonvertical angles throughout development. Soil phosphate is one limiting nutrient for plant growth that is known to induce changes to root system architecture, such as increased lateral root formation. This study seeks to determine whether phosphate concentration affects lateral root orientation in addition to its previously described influences on root architecture. Images of intact Arabidopsis root systems were recorded for 24 h, and lateral root tip angles were measured for wild-type and mutant pgm-1 and pin3-1 roots on a full or low phosphate medium. Setpoint angles of unstimulated root systems were determined, as were gravitropic responses of lateral roots over time. The root system setpoint angles of wild-type and mutant pin3-1 roots showed a shift toward a more vertical orientation on low orthophosphate (Pi) medium. The gravitropic responses of both pgm-1 and pin3-1 roots on low Pi medium was elevated relative to control Pi medium. Mutations in two phosphate transporters with high levels of expression in the root showed a gravitropic response similar to wild-type roots grown on low Pi, supporting a role for Pi status in regulating lateral root gravitropism. Lateral root orientation and gravitropism are affected by Pi status and may provide an important additional parameter for describing root responses to low Pi. The data also support the conclusion that gravitropic setpoint angle reacts to nutrient status and is under dynamic regulation.

Correlation between calmodulin activity and gravitropic sensitivity in primary roots of maize

NASA Technical Reports Server (NTRS)

Stinemetz, C. L.; Kuzmanoff, K. M.; Evans, M. L.; Jarrett, H. W.

1987-01-01

Recent evidence indicates a role for calcium and calmodulin in the gravitropic response of primary roots of maize (Zea mays, L.). We examined this possibility by testing the relationship between calmodulin activity and gravitropic sensitivity in roots of the maize cultivars Merit and B73 x Missouri 17. Roots of the Merit cultivar require light to the gravitropically competent. The gravitropic response of the Missouri cultivar is independent of light. The occurrence of calmodulin in primary roots of these maize cultivars was tested by affinity gel chromatography followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis with bovine brain calmodulin as standard. The distribution of calmodulin activity was measured using both the phosphodiesterase and NAD kinase assays for calmodulin. These assays were performed on whole tissue segments, crude extracts, and purified extracts. In light-grown seedlings of the Merit cultivar or in either dark- or light-grown seedlings of the Missouri cultivar, calmodulin activity per millimeter of root tissue was about 4-fold higher in the apical millimeter than in the subtending 3 millimeters. Calmodulin activity was very low in the apical millimeter of roots of dark-grown (gravitropically nonresponsive) seedlings of the Merit cultivar. Upon illumination, the calmodulin activity in the apical millimeter increased to a level comparable to that of light-grown seedlings and the roots became gravitropically competent. The time course of the development of gravitropic sensitivity following illumination paralleled the time course of the increase in calmodulin activity in the apical millimeter of the root. The results are consistent with the suggestion that calmodulin plays an important role in the gravitropic response of roots.

Quantification of root gravitropic response using a constant stimulus feedback system.

PubMed

Wolverton, Chris

2015-01-01

Numerous software packages now exist for quantifying root growth responses, most of which analyze a time resolved sequence of images ex post facto. However, few allow for the real-time analysis of growth responses. The system in routine use in our lab allows for real-time growth analysis and couples this to positional feedback to control the stimulus experienced by the responding root. This combination allows us to overcome one of the confounding variables in studies of root gravity response. Seedlings are grown on standard petri plates attached to a vertical rotating stage and imaged using infrared illumination. The angle of a particular region of the root is determined by image analysis, compared to the prescribed angle, and any corrections in positioning are made by controlling a stepper motor. The system allows for the long-term stimulation of a root at a constant angle and yields insights into the gravity perception and transduction machinery not possible with other approaches.

Developmental and environmental effects on assimilate partitioning in Canada thistle

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tworkoski, T.J.

1989-04-01

Canada thistle (Cirsium arvense) plants at three stages of development (rosette, bolt, and flower bud) were grown under spring-simulated or fall-simulated environments. Sucrose export from a single leaf exposed to {sup 14}CO{sub 2} was significantly greater in rosette-plants than bolt- or flower bud-plants during the first two hours after pulse. Twenty-four hours after pulse, total {sup 14}C translocation (dpm) was the same in both environments but the {sup 14}C concentration (dpm/gm) was greater in roots of fall-grown plants. Shoot meristem respiration of fall-grown plants was approximately 50% less than spring-grown plants and was a factor responsible for this trend. Concentrationsmore » of inulin and water-insoluble starch were greater in roots of fall-grown than spring-grown plants and pulsed {sup 14}C accumulated in these fractions. The results suggest that a shift in respiration and metabolism of fall-grown rosette- and bolt-plants leads to increased assimilate movement to the root which may have practical implications for control of this weed.« less

Root anatomical phenes predict root penetration ability and biomechanical properties in maize (Zea Mays)

PubMed Central

Chimungu, Joseph G.; Loades, Kenneth W.; Lynch, Jonathan P.

2015-01-01

The ability of roots to penetrate hard soil is important for crop productivity but specific root phenes contributing to this ability are poorly understood. Root penetrability and biomechanical properties are likely to vary in the root system dependent on anatomical structure. No information is available to date on the influence of root anatomical phenes on root penetrability and biomechanics. Root penetration ability was evaluated using a wax layer system. Root tensile and bending strength were evaluated in plant roots grown in the greenhouse and in the field. Root anatomical phenes were found to be better predictors of root penetrability than root diameter per se and associated with smaller distal cortical region cell size. Smaller outer cortical region cells play an important role in stabilizing the root against ovalization and reducing the risk of local buckling and collapse during penetration, thereby increasing root penetration of hard layers. The use of stele diameter was found to be a better predictor of root tensile strength than root diameter. Cortical thickness, cortical cell count, cortical cell wall area and distal cortical cell size were stronger predictors of root bend strength than root diameter. Our results indicate that root anatomical phenes are important predictors for root penetrability of high-strength layers and root biomechanical properties. PMID:25903914

Hydraulic conductivity of soil-grown lupine and maize unbranched roots and maize root-shoot junctions.

PubMed

Meunier, Félicien; Zarebanadkouki, Mohsen; Ahmed, Mutez A; Carminati, Andrea; Couvreur, Valentin; Javaux, Mathieu

2018-01-26

Improving or maintaining crop productivity under conditions of long term change of soil water availability and atmosphere demand for water is one the big challenges of this century. It requires a deep understanding of crop water acquisition properties, i.e. root system architecture and root hydraulic properties among other characteristics of the soil-plant-atmosphere continuum. A root pressure probe technique was used to measure the root hydraulic conductances of seven-week old maize and lupine plants grown in sandy soil. Unbranched root segments were excised in lateral, seminal, crown and brace roots of maize, and in lateral roots of lupine. Their total hydraulic conductance was quantified under steady-state hydrostatic gradient for progressively shorter segments. Furthermore, the axial conductance of proximal root regions removed at each step of root shortening was measured as well. Analytical solutions of the water flow equations in unbranched roots developed recently and relating root total conductance profiles to axial and radial conductivities were used to retrieve the root radial hydraulic conductivity profile along each root type, and quantify its uncertainty. Interestingly, the optimized root radial conductivities and measured axial conductances displayed significant differences across root types and species. However, the measured root total conductances did not differ significantly. As compared to measurements reported in the literature, our axial and radial conductivities concentrate in the lower range of herbaceous species hydraulic properties. In a final experiment, the hydraulic conductances of root junctions to maize stem were observed to highly depend on root type. Surprisingly maize brace root junctions were an order of magnitude more conductive than the other crown and seminal roots, suggesting potential regulation mechanism for root water uptake location and a potential role of the maize brace roots for water uptake more important than reported in the literature. Copyright © 2018 Elsevier GmbH. All rights reserved.

Effect of CO2 levels on nutrient content of lettuce and radish.

PubMed

McKeehen, J D; Smart, D J; Mackowiak, C L; Wheeler, R M; Nielsen, S S

1996-01-01

Atmospheric carbon-dioxide enrichment is known to affect the yield of lettuce and radish grown in controlled environments, but little is known about CO2 enrichment effects on the chemical composition of lettuce and radish. These crops are useful model systems for a Controlled Ecological Life-Support System (CELSS), largely because of their relatively short production cycles. Lettuce (Lactuca sativa L.) cultivar 'Waldmann's Green' and radish (Raphanus sativus L.) cultivar 'Giant White Globe' were grown both in the field and in controlled environments, where hydroponic nutrient solution, light, and temperature were regulated, and where CO2 levels were controlled at 400, 1000, 5000, or 10,000 ppm. Plants were harvested at maturity, dried, and analyzed for proximate composition (protein, fat, ash, and carbohydrate), total nitrogen (N), nitrate N, free sugars, starch, total dietary fiber, and minerals. Total N, protein N, nonprotein N (NPN), and nitrate N generally increased for radish roots and lettuce leaves when grown under growth chamber conditions compared to field conditions. The nitrate-N level of lettuce leaves, as a percentage of total NPN, decreased with increasing levels of CO2 enrichment. The ash content of radish roots and of radish and lettuce leaves decreased with increasing levels of CO2 enrichment. The levels of certain minerals differed between field- and chamber-grown materials, including changes in the calcium (Ca) and phosphorus (P) contents of radish and lettuce leaves, resulting in reduced Ca/P ratio for chamber-grown materials. The free-sugar contents were similar between the field and chamber-grown lettuce leaves, but total dietary fiber content was much higher in the field-grown plant material. The starch content of growth-chamber lettuce increased with CO2 level.

Effect of CO2 levels on nutrient content of lettuce and radish

NASA Technical Reports Server (NTRS)

McKeehen, J. D.; Smart, D. J.; Mackowiak, C. L.; Wheeler, R. M.; Nielsen, S. S.; Mitchell, C. A. (Principal Investigator)

1996-01-01

Atmospheric carbon-dioxide enrichment is known to affect the yield of lettuce and radish grown in controlled environments, but little is known about CO2 enrichment effects on the chemical composition of lettuce and radish. These crops are useful model systems for a Controlled Ecological Life-Support System (CELSS), largely because of their relatively short production cycles. Lettuce (Lactuca sativa L.) cultivar 'Waldmann's Green' and radish (Raphanus sativus L.) cultivar 'Giant White Globe' were grown both in the field and in controlled environments, where hydroponic nutrient solution, light, and temperature were regulated, and where CO2 levels were controlled at 400, 1000, 5000, or 10,000 ppm. Plants were harvested at maturity, dried, and analyzed for proximate composition (protein, fat, ash, and carbohydrate), total nitrogen (N), nitrate N, free sugars, starch, total dietary fiber, and minerals. Total N, protein N, nonprotein N (NPN), and nitrate N generally increased for radish roots and lettuce leaves when grown under growth chamber conditions compared to field conditions. The nitrate-N level of lettuce leaves, as a percentage of total NPN, decreased with increasing levels of CO2 enrichment. The ash content of radish roots and of radish and lettuce leaves decreased with increasing levels of CO2 enrichment. The levels of certain minerals differed between field- and chamber-grown materials, including changes in the calcium (Ca) and phosphorus (P) contents of radish and lettuce leaves, resulting in reduced Ca/P ratio for chamber-grown materials. The free-sugar contents were similar between the field and chamber-grown lettuce leaves, but total dietary fiber content was much higher in the field-grown plant material. The starch content of growth-chamber lettuce increased with CO2 level.

Biocompatibility of sweetpotato and peanut in a hydroponic system

NASA Technical Reports Server (NTRS)

Mortley, D. G.; Loretan, P. A.; Hill, W. A.; Bonsi, C. K.; Morris, C. E.; Hall, R.; Sullen, D.

1998-01-01

'Georgia Red' peanut (Arachis hypogaea L.) and TU-82-155 sweetpotato [Ipomoea batatas (L.) Lam] were grown in monocultured or intercropped recirculating hydroponic systems in a greenhouse using the nutrient film technique (NFT). The objective was to determine whether growth and subsequent yield would be affected by intercropping. Treatments were sweetpotato monoculture (SP), peanut monoculture (PN), and sweetpotato and peanut grown in separate NFT channels but sharing a common nutrient solution (SP-PN). Greenhouse conditions ranged from 24 to 33 degrees C, 60% to 90% relative humidity (RH), and photosynthetic photon flux (PPF) of 200 to 1700 micromoles m-2 s-1. Sweetpotato cuttings (15 cm long) and 14-day-old seedlings of peanuts were planted into growth channels (0.15 x 0.15 x 1.2 m). Plants were spaced 25 cm apart within and 25 cm apart between growing channels. A modified half-Hoagland solution with a 1 N: 2.4 K ratio was used. Solution pH was maintained between 5.5 and 6.0 for treatments involving SP and 6.4 and 6.7 for PN. Electrical conductivity (EC) ranged between 1100 and 1200 microS cm-1. The number of storage roots per sweetpotato plant was similar for both SP and SP-PN. Storage root fresh and dry mass were 29% and 36% greater, respectively, for plants in the SP-PN treatment than for plants in the SP treatment. The percent dry mass of the storage roots, dry mass of fibrous and pencil roots, and the length-to-diameter ratio of storage roots were similar for SP and SP-PN sweetpotato plants. Likewise, foliage fresh and dry mass and harvest index were not significantly influenced by treatment. Total dry mass was 37% greater for PN than for SP-PN peanut plants, and pod dry mass was 82% higher. Mature and total seed dry mass and fibrous root dry mass were significantly greater for PN than for SP-PN plants. Harvest index (HI) was similar for both treatments. Root length tended to be lower for seedlings grown in the nutrient solution from the SP-PN treatment.

Capturing Arabidopsis root architecture dynamics with ROOT-FIT reveals diversity in responses to salinity.

PubMed

Julkowska, Magdalena M; Hoefsloot, Huub C J; Mol, Selena; Feron, Richard; de Boer, Gert-Jan; Haring, Michel A; Testerink, Christa

2014-11-01

The plant root is the first organ to encounter salinity stress, but the effect of salinity on root system architecture (RSA) remains elusive. Both the reduction in main root (MR) elongation and the redistribution of the root mass between MRs and lateral roots (LRs) are likely to play crucial roles in water extraction efficiency and ion exclusion. To establish which RSA parameters are responsive to salt stress, we performed a detailed time course experiment in which Arabidopsis (Arabidopsis thaliana) seedlings were grown on agar plates under different salt stress conditions. We captured RSA dynamics with quadratic growth functions (root-fit) and summarized the salt-induced differences in RSA dynamics in three growth parameters: MR elongation, average LR elongation, and increase in number of LRs. In the ecotype Columbia-0 accession of Arabidopsis, salt stress affected MR elongation more severely than LR elongation and an increase in LRs, leading to a significantly altered RSA. By quantifying RSA dynamics of 31 different Arabidopsis accessions in control and mild salt stress conditions, different strategies for regulation of MR and LR meristems and root branching were revealed. Different RSA strategies partially correlated with natural variation in abscisic acid sensitivity and different Na(+)/K(+) ratios in shoots of seedlings grown under mild salt stress. Applying root-fit to describe the dynamics of RSA allowed us to uncover the natural diversity in root morphology and cluster it into four response types that otherwise would have been overlooked. © 2014 American Society of Plant Biologists. All Rights Reserved.

Patterns of nocturnal rehydration in root tissues of Vaccinium corymbosum L. under severe drought conditions

PubMed Central

Valenzuela-Estrada, Luis R.; Richards, James H.; Diaz, Andres; Eissensat, David M.

2009-01-01

Although roots in dry soil layers are commonly rehydrated by internal hydraulic redistribution during the nocturnal period, patterns of tissue rehydration are poorly understood. Rates of nocturnal rehydration were examined in roots of different orders in Vaccinium corymbosum L. ‘Bluecrop’ (Northern highbush blueberry) grown in a split-pot system with one set of roots in relatively moist soil and the other set of roots in dry soil. Vaccinium is noted for a highly branched and extremely fine root system. It is hypothesized that nocturnal root tissue rehydration would be slow, especially in the distal root orders because of their greater hydraulic constraints (smaller vessel diameters and fewer number of vessels). Vaccinium root hydraulic properties delayed internal water movement. Even when water was readily available to roots in the wet soil and transpiration was minimal, it took a whole night-time period of 12 h for the distal finest roots (1st to 4th order) under dry soil conditions to reach the same water potentials as fine roots in moist soil (1st to 4th order). Even though roots under dry soil equilibrated with roots in moist soil, the equilibrium point reached before sunrise was about –1.2 MPa, indicating that tissues were not fully rehydrated. Using a single-branch root model, it was estimated that individual roots exhibiting the lowest water potentials in dry soil were 1st order roots (distal finest roots of the root system). However, considered at the branch level, root orders with the highest hydraulic resistances corresponded to the lowest orders of the permanent root system (3rd-, 4th-, and 5th-order roots), thus indicating possible locations of hydraulic safety control in the root system of this species. PMID:19188275

Patterns of nocturnal rehydration in root tissues of Vaccinium corymbosum L. under severe drought conditions.

PubMed

Valenzuela-Estrada, Luis R; Richards, James H; Diaz, Andres; Eissensat, David M

2009-01-01

Although roots in dry soil layers are commonly rehydrated by internal hydraulic redistribution during the nocturnal period, patterns of tissue rehydration are poorly understood. Rates of nocturnal rehydration were examined in roots of different orders in Vaccinium corymbosum L. 'Bluecrop' (Northern highbush blueberry) grown in a split-pot system with one set of roots in relatively moist soil and the other set of roots in dry soil. Vaccinium is noted for a highly branched and extremely fine root system. It is hypothesized that nocturnal root tissue rehydration would be slow, especially in the distal root orders because of their greater hydraulic constraints (smaller vessel diameters and fewer number of vessels). Vaccinium root hydraulic properties delayed internal water movement. Even when water was readily available to roots in the wet soil and transpiration was minimal, it took a whole night-time period of 12 h for the distal finest roots (1st to 4th order) under dry soil conditions to reach the same water potentials as fine roots in moist soil (1st to 4th order). Even though roots under dry soil equilibrated with roots in moist soil, the equilibrium point reached before sunrise was about -1.2 MPa, indicating that tissues were not fully rehydrated. Using a single-branch root model, it was estimated that individual roots exhibiting the lowest water potentials in dry soil were 1st order roots (distal finest roots of the root system). However, considered at the branch level, root orders with the highest hydraulic resistances corresponded to the lowest orders of the permanent root system (3rd-, 4th-, and 5th-order roots), thus indicating possible locations of hydraulic safety control in the root system of this species.

Micropropagation and hairy root culture of Ophiorrhiza alata Craib for camptothecin production.

PubMed

Ya-ut, Pornwilai; Chareonsap, Piyarat; Sukrong, Suchada

2011-12-01

An efficient system was developed for the in vitro micropropagation and hairy root culture of Ophiorrhiza alata Craib for camptothecin (CPT) production. Shoot multiplication on leaf and node explants from germinated seeds of O. alata was successful on half-strength Murashige and Skoog medium supplemented with varying amounts of kinetin and α-naphthaleneacetic acid. Node explants grown in vitro were successfully infected by Agrobacterium rhizogenes TISTR 1450 for the establishment of hairy root culture. The amount of CPT in various parts of O. alata was analyzed by HPLC. The accumulation of CPT in transformed hairy roots was twice that in soil-grown plants (785 ± 52 and 388 ± 32 μg/g dry wt, respectively). In the presence of a polystyrene resin (Diaion HP-20) that absorbed CPT, the CPT content in the culture media increased sevenfold compared with controls (1,036 and 151 μg per 250 ml medium, respectively). These results enable the feasible production of CPT of O. alata by means of a cell culture strategy. These measures can help safeguard the plant from extinction. © Springer Science+Business Media B.V. 2011

Organization of cortical microtubules in graviresponding maize roots

NASA Technical Reports Server (NTRS)

Blancaflor, E. B.; Hasenstein, K. H.

1993-01-01

Immunofluorescence labeling of cortical microtubules (MTs) was used to investigate the relationship between MT arrangement and changes in growth rate of the upper and lower sides of horizontally placed roots of maize (Zea mays L. cv. Merit). Cap cells and cells of the elongation zone of roots grown vertically in light or darkness showed MT arrangements that were transverse (perpendicular) to the growth direction. Microtubules of cells basal to the elongation zone typically showed oblique orientation. Two hours after horizontal reorientation, cap cells of gravicompetent, light-grown and curving roots contained MTs parallel to the gravity vector. The MT arrangement on the upper side of the elongation zone remained transverse but the MTs of the outer four to five layers of cortical cells along the lower side of the elongation zone showed reorientation parallel to the axis of the root. The MTs of the lower epidermis retained their transverse orientation. Dark-grown roots did not curve and did not show reorientation of MTs in cells of the root cap or elongation zone. The data indicate that MT depolymerization and reorientation is correlated with reduction in growth rate, and that MT reorientation is one of the steps of growth control of graviresponding roots.

The signal transducer NPH3 integrates the phototropin1 photosensor with PIN2-based polar auxin transport in Arabidopsis root phototropism.

PubMed

Wan, Yinglang; Jasik, Jan; Wang, Li; Hao, Huaiqing; Volkmann, Dieter; Menzel, Diedrik; Mancuso, Stefano; Baluška, František; Lin, Jinxing

2012-02-01

Under blue light (BL) illumination, Arabidopsis thaliana roots grow away from the light source, showing a negative phototropic response. However, the mechanism of root phototropism is still unclear. Using a noninvasive microelectrode system, we showed that the BL sensor phototropin1 (phot1), the signal transducer NONPHOTOTROPIC HYPOCOTYL3 (NPH3), and the auxin efflux transporter PIN2 were essential for BL-induced auxin flux in the root apex transition zone. We also found that PIN2-green fluorescent protein (GFP) localized to vacuole-like compartments (VLCs) in dark-grown root epidermal and cortical cells, and phot1/NPH3 mediated a BL-initiated pathway that caused PIN2 redistribution to the plasma membrane. When dark-grown roots were exposed to brefeldin A (BFA), PIN2-GFP remained in VLCs in darkness, and BL caused PIN2-GFP disappearance from VLCs and induced PIN2-GFP-FM4-64 colocalization within enlarged compartments. In the nph3 mutant, both dark and BL BFA treatments caused the disappearance of PIN2-GFP from VLCs. However, in the phot1 mutant, PIN2-GFP remained within VLCs under both dark and BL BFA treatments, suggesting that phot1 and NPH3 play different roles in PIN2 localization. In conclusion, BL-induced root phototropism is based on the phot1/NPH3 signaling pathway, which stimulates the shootward auxin flux by modifying the subcellular targeting of PIN2 in the root apex transition zone.

Root Type-Specific Reprogramming of Maize Pericycle Transcriptomes by Local High Nitrate Results in Disparate Lateral Root Branching Patterns1[OPEN

PubMed Central

Lithio, Andrew

2016-01-01

The adaptability of root system architecture to unevenly distributed mineral nutrients in soil is a key determinant of plant performance. The molecular mechanisms underlying nitrate dependent plasticity of lateral root branching across the different root types of maize are only poorly understood. In this study, detailed morphological and anatomical analyses together with cell type-specific transcriptome profiling experiments combining laser capture microdissection with RNA-seq were performed to unravel the molecular signatures of lateral root formation in primary, seminal, crown, and brace roots of maize (Zea mays) upon local high nitrate stimulation. The four maize root types displayed divergent branching patterns of lateral roots upon local high nitrate stimulation. In particular, brace roots displayed an exceptional architectural plasticity compared to other root types. Transcriptome profiling revealed root type-specific transcriptomic reprogramming of pericycle cells upon local high nitrate stimulation. The alteration of the transcriptomic landscape of brace root pericycle cells in response to local high nitrate stimulation was most significant. Root type-specific transcriptome diversity in response to local high nitrate highlighted differences in the functional adaptability and systemic shoot nitrogen starvation response during development. Integration of morphological, anatomical, and transcriptomic data resulted in a framework underscoring similarity and diversity among root types grown in heterogeneous nitrate environments. PMID:26811190

Automated Root Tracking with "Root System Analyzer"

NASA Astrophysics Data System (ADS)

Schnepf, Andrea; Jin, Meina; Ockert, Charlotte; Bol, Roland; Leitner, Daniel

2015-04-01

Crucial factors for plant development are water and nutrient availability in soils. Thus, root architecture is a main aspect of plant productivity and needs to be accurately considered when describing root processes. Images of root architecture contain a huge amount of information, and image analysis helps to recover parameters describing certain root architectural and morphological traits. The majority of imaging systems for root systems are designed for two-dimensional images, such as RootReader2, GiA Roots, SmartRoot, EZ-Rhizo, and Growscreen, but most of them are semi-automated and involve mouse-clicks in each root by the user. "Root System Analyzer" is a new, fully automated approach for recovering root architectural parameters from two-dimensional images of root systems. Individual roots can still be corrected manually in a user interface if required. The algorithm starts with a sequence of segmented two-dimensional images showing the dynamic development of a root system. For each image, morphological operators are used for skeletonization. Based on this, a graph representation of the root system is created. A dynamic root architecture model helps to determine which edges of the graph belong to an individual root. The algorithm elongates each root at the root tip and simulates growth confined within the already existing graph representation. The increment of root elongation is calculated assuming constant growth. For each root, the algorithm finds all possible paths and elongates the root in the direction of the optimal path. In this way, each edge of the graph is assigned to one or more coherent roots. Image sequences of root systems are handled in such a way that the previous image is used as a starting point for the current image. The algorithm is implemented in a set of Matlab m-files. Output of Root System Analyzer is a data structure that includes for each root an identification number, the branching order, the time of emergence, the parent identification number, the distance between branching point to the parent root base, the root length, the root radius and the nodes that belong to each individual root path. This information is relevant for the analysis of dynamic root system development as well as the parameterisation of root architecture models. Here, we show results of Root System Analyzer applied to analyse the root systems of wheat plants grown in rhizotrons. Different treatments with respect to soil moisture and apatite concentrations were used to test the effects of those conditions on root system development. Photographs of the root systems were taken at high spatial and temporal resolution and root systems are automatically tracked.

Biological Control of Diseases of Vegetables Grown Hydroponically in Thailand: Challenge and Opportunity.

PubMed

Kanjanamaneesathian, Mana

2015-01-01

In Thailand, yield loss due to plant diseases in vegetables grown hydroponically is very high as a result of the growers` lack of knowledge for controlling diseases and their un- willingness to invest in setting-up the proper hydroponic system from the beginning. Severe root rot disease caused by Pythium spp. is frequent and can be anticipated in the hot climate in Thailand. This review focuses on the diseases in temperate lettuces which have been produced hydroponically and have been attacked by plant pathogens, particularly Pythium spp. Biological control of vegetable diseases grown hydroponically has been investigated in Thailand. Research is being carried out to identify effective strains of the antagonists, formulating the applicable products and delivering them appropriately to control the disease. Products of Bacillus subtilis, Chaetomium globosom and Trichoderma harzianum have been recommended for use to control diseases in vegetables grown hydroponically. Control efficacy of these products is varied as the biological products have been used by the growers in the paradigm of using chemical fungicide for disease control in hydroponic production system, overlooking the intrinsic characteristics of the biological control products. The recent patent, which minimizes the effects of sunlight and heat on the nutrient solution without the use of an external energy for cooling the nutrient, should be applied in producing hydroponic vegetables to mitigate poor plant growth and root rot disease outbreak in Thailand.

Taxodione and Extracts from Salvia austriaca Roots as Human Cholinesterase Inhibitors.

PubMed

Kuźma, Łukasz; Wysokińska, Halina; Sikora, Joanna; Olszewska, Paulina; Mikiciuk-Olasik, Elżbieta; Szymański, Paweł

2016-02-01

Taxodione, an abietane diterpenoid, was isolated from Salvia austriaca transformed roots grown in in vitro conditions. The compound is known to have antibacterial, cytotoxic and anti-tumour properties. This study evaluates the ability of pure taxodione and extracts obtained from the S. austriaca hairy roots and roots from field-grown plants to inhibit human acetylcholinesterase and butyrylcholinesterase. Both extracts were found to have similar actions against acetylcholinesterase. The IC50 for extracts from transformed and untransformed roots were 142.5 and 139.5 µg ml(-1), respectively. The highest activity towards human acetylcholinesterase was demonstrated by taxodione (IC50  = 54.84 µg ml(-1)). With respect to BChE inhibition, the root extracts demonstrated stronger activity (IC50  = 23.6 µg ml(-1): field-grown plants and 41.6 µg ml(-1): transformed roots) than taxodione (IC50  = 195.9 µg ml(-1)). Taxodione showed significant cytotoxicity against A549 cell line (IC50  = 9.1 µg ml(-1)), whereas the activities for the extracts from S. austriaca roots of field-grown plants (IC50  = 75.7 µg ml(-1)) and hairy roots (IC50  = 86.2 µg ml(-1)) were lower. Computer modelling suggests that taxodione should not demonstrate cardiotoxic or genotoxic activity. It also indicates that taxodione should demonstrate very rapid transport from the body with very good blood-brain barrier penetration, but with no cumulative effect on the human body. The obtained results indicate that taxodione is a safe compound and may be used for further investigations in pharmacological activities. Copyright © 2015 John Wiley & Sons, Ltd.

Tree species diversity interacts with elevated CO2 to induce a greater root system response.

PubMed

Smith, Andrew R; Lukac, Martin; Bambrick, Michael; Miglietta, Franco; Godbold, Douglas L

2013-01-01

As a consequence of land-use change and the burning of fossil fuels, atmospheric concentrations of CO2 are increasing and altering the dynamics of the carbon cycle in forest ecosystems. In a number of studies using single tree species, fine root biomass has been shown to be strongly increased by elevated CO2 . However, natural forests are often intimate mixtures of a number of co-occurring species. To investigate the interaction between tree mixture and elevated CO2 , Alnus glutinosa, Betula pendula and Fagus sylvatica were planted in areas of single species and a three species polyculture in a free-air CO2 enrichment study (BangorFACE). The trees were exposed to ambient or elevated CO2 (580 μmol mol(-1) ) for 4 years. Fine and coarse root biomass, together with fine root turnover and fine root morphological characteristics were measured. Fine root biomass and morphology responded differentially to the elevated CO2 at different soil depths in the three species when grown in monocultures. In polyculture, a greater response to elevated CO2 was observed in coarse roots to a depth of 20 cm, and fine root area index to a depth of 30 cm. Total fine root biomass was positively affected by elevated CO2 at the end of the experiment, but not by species diversity. Our data suggest that existing biogeochemical cycling models parameterized with data from species grown in monoculture may be underestimating the belowground response to global change. © 2012 Blackwell Publishing Ltd.

Edaphic history over seedling characters predicts integration and plasticity of integration across geologically variable populations of Arabidopsis thaliana.

PubMed

Cousins, Elsa A; Murren, Courtney J

2017-12-01

Studies on phenotypic plasticity and plasticity of integration have uncovered functionally linked modules of aboveground traits and seedlings of Arabidopsis thaliana , but we lack details about belowground variation in adult plants. Functional modules can be comprised of additional suites of traits that respond to environmental variation. We assessed whether shoot and root responses to nutrient environments in adult A. thaliana were predictable from seedling traits or population-specific geologic soil characteristics at the site of origin. We compared 17 natural accessions from across the native range of A. thaliana using 14-day-old seedlings grown on agar or sand and plants grown to maturity across nutrient treatments in sand. We measured aboveground size, reproduction, timing traits, root length, and root diameter. Edaphic characteristics were obtained from a global-scale dataset and related to field data. We detected significant among-population variation in root traits of seedlings and adults and in plasticity in aboveground and belowground traits of adult plants. Phenotypic integration of roots and shoots varied by population and environment. Relative integration was greater in roots than in shoots, and integration was predicted by edaphic soil history, particularly organic carbon content, whereas seedling traits did not predict later ontogenetic stages. Soil environment of origin has significant effects on phenotypic plasticity in response to nutrients, and on phenotypic integration of root modules and shoot modules. Root traits varied among populations in reproductively mature individuals, indicating potential for adaptive and integrated functional responses of root systems in annuals. © 2017 Botanical Society of America.

Accounting for sap flow from different parts of the root system improves the prediction of xylem ABA concentration in plants grown with heterogeneous soil moisture.

PubMed

Dodd, Ian C; Egea, Gregorio; Davies, William J

2008-01-01

When soil moisture is heterogeneous, sap flow from, and ABA status of, different parts of the root system impact on leaf xylem ABA concentration ([X-ABA]leaf). The robustness of a model for predicting [X-ABA]leaf was assessed. 'Two root-one shoot' grafted sunflower (Helianthus annuus L.) plants received either deficit irrigation (DI, each root system received the same irrigation volumes) or partial rootzone drying (PRD, only one root system was watered and the other dried the soil). Irrespective of whether relative sap flow was assessed using sap flow sensors in vivo or by pressurization of de-topped roots, each root system contributed similarly to total sap flow during DI, while sap flow from roots in drying soil declined linearly with soil water potential (Psisoil) during PRD. Although Psisoil of the irrigated pot determined the threshold Psisoil at which sap flow from roots in drying soil decreased, the slope of this decrease was independent of the wet pot Psisoil. Irrespective of whether sap was collected from the wet or dry root system of PRD plants, or a DI plant, root xylem ABA concentration increased as Psisoil declined. The model, which weighted ABA contributions of each root system according to the sap flow from each, almost perfectly explained [X-ABA] immediately above the graft union. That the model overestimated measured [X-ABA]leaf may result from changes in [X-ABA] along the transport pathway or an artefact of collecting xylem sap from detached leaves. The implications of declining sap flow through partially dry roots during PRD for the control of stomatal behaviour and irrigation scheduling are discussed.

The role of calcium ions in cytological effects of hypogravity

NASA Astrophysics Data System (ADS)

Kordyum, E. L.; Belyavskaya, N. A.; Nedukha, E. M.; Palladina, T. A.; Tarasenko, V. A.

Electron-cytochemical and biochemical methods made it possible to reveal certain differences in ATPase activity stimulation by calcium ions in root apex cells of pea seedlings and moss protonema Funaria hygrometrica grown under stationary and slow clinostatic (2 rev/min) conditions. It was showed that under clinostatic conditions in comparison with the control variant the ATPase activity decreases in plasmalemma. The protein content in the plasmalemma fraction was also twice as low under these conditions. The root apex cells of the pea seedlings grown under spaceflight conditions were found to contain high concentrations of membrane-bound calcium. The data obtained are discussed in relation to problems of possible mechanisms of disturbance in calcium balance and the system of active calcium ion transport through plasmalemma under hypogravity.

Growth in microgravity increases susceptibility of soybean to a fungal pathogen

NASA Technical Reports Server (NTRS)

Ryba-White, M.; Nedukha, O.; Hilaire, E.; Guikema, J. A.; Kordyum, E.; Leach, J. E.; Spooner, B. S. (Principal Investigator)

2001-01-01

The influence of microgravity on the susceptibility of soybean roots to Phytophthora sojae was studied during the Space Shuttle Mission STS-87. Seedlings of soybean cultivar Williams 82 grown in spaceflight or at unit gravity were untreated or inoculated with the soybean root rot pathogen P. sojae. At 3, 6 and 7 d after launch while still in microgravity, seedlings were photographed and then fixed for subsequent microscopic analysis. Post-landing analysis of the seedlings revealed that at harvest day 7 the length of untreated roots did not differ between flight and ground samples. However, the flight-grown roots infected with P. sojae showed more disease symptoms (percentage of brown and macerated areas) and the root tissues were more extensively colonized relative to the ground controls exposed to the fungus. Ethylene levels were higher in spaceflight when compared to ground samples. These data suggest that soybean seedlings grown in microgravity are more susceptible to colonization by a fungal pathogen relative to ground controls.

In vitro antifungal activity of extracts obtained from Hypericum perforatum adventitious roots cultured in a mist bioreactor against planktonic cells and biofilm of Malassezia furfur.

PubMed

Simonetti, Giovanna; Tocci, Noemi; Valletta, Alessio; Brasili, Elisa; D'Auria, Felicia Diodata; Idoux, Alicia; Pasqua, Gabriella

2016-01-01

Xanthone-rich extracts from Hypericum perforatum root cultures grown in a Mist Bioreactor as antifungal agents against Malassezia furfur. Extracts of Hypericum perforatum roots grown in a bioreactor showed activity against planktonic cells and biofilm of Malassezia furfur. Dried biomass, obtained from roots grown under controlled conditions in a ROOTec mist bioreactor, has been extracted with solvents of increasing polarity (i.e. chloroform, ethyl acetate and methanol). The methanolic fraction was the richest in xanthones (2.86 ± 0.43 mg g(-1) DW) as revealed by HPLC. The minimal inhibitory concentration of the methanol extract against M. furfur planktonic cells was 16 μg mL(-1). The inhibition percentage of biofilm formation, at a concentration of 16 μg mL(-1), ranged from 14% to 39%. The results show that H. perforatum root extracts could be used as new antifungal agents in the treatment of Malassezia infections.

Diagravitropism in corn roots

NASA Technical Reports Server (NTRS)

Leopold, A. C.; Wettlaufer, S. H.

1988-01-01

The diagravitropic behavior of Merit corn (Zea mays L.) roots grown in darkness provides an opportunity for comparison of two qualitatively different gravitropic systems. As with positive gravitropism, diagravitropism is shown to require the presence of the root cap, have a similar time course for the onset of curvature, and a similar presentation time. In contrast with positive gravitropism, diagravitropism appears to have a more limited requirement for calcium, for it is insensitive to the elution of calcium by EGTA and insensitive to the subsequent addition of a calcium/EGTA complex. These results are interpreted as indicating that whereas the same sensing system is shared by the two types of gravitropism, separate transductive systems are involved, one for diagravitropism, which is relatively independent of calcium, and one for positive gravitropism, which is markedly dependent on calcium.

Effect of cultural practices and fungicide treatments on the severity of Phytophthora root rot of blueberries grown in Mississippi

USDA-ARS?s Scientific Manuscript database

Phytophthora root rot is an important disease of blueberries, especially those grown in areas with poor drainage. Reliable cultural and chemical management strategies are needed for control of this disease. Two studies were conducted to evaluate the effects of cultural practices and fungicide treat...

The Potential of Five Winter-grown Crops to Reduce Root-knot Nematode Damage and Increase Yield of Tomato

PubMed Central

López-Pérez, Jose Antonio; Roubtsova, Tatiana; de Cara García, Miguel

2010-01-01

Broccoli (Brassica oleracea), carrot (Daucus carota), marigold (Tagetes patula), nematode-resistant tomato (Solanum lycopersicum), and strawberry (Fragaria ananassa) were grown for three years during the winter in a root-knot nematode (Meloidogyne incognita) infested field in Southern California. Each year in the spring, the tops of all crops were shredded and incorporated in the soil. Amendment with poultry litter was included as a sub-treatment. The soil was then covered with clear plastic for six weeks and M. incognita-susceptible tomato was grown during the summer season. Plastic tarping raised the average soil temperature at 13 cm depth by 7°C.The different winter-grown crops or the poultry litter did not affect M. incognita soil population levels. However, root galling on summer tomato was reduced by 36%, and tomato yields increased by 19% after incorporating broccoli compared to the fallow control. This crop also produced the highest amount of biomass of the five winter-grown crops. Over the three-year trial period, poultry litter increased tomato yields, but did not affect root galling caused by M. incognita. We conclude that cultivation followed by soil incorporation of broccoli reduced M. incognita damage to tomato. This effect is possibly due to delaying or preventing a portion of the nematodes to reach the host roots. We also observed that M. incognita populations did not increase under a host crop during the cool season when soil temperatures remained low (< 18°C). PMID:22736848

Effects of abscisic acid and xanthoxin on elongation and gravitropism in primary roots of Zea mays

NASA Technical Reports Server (NTRS)

Lee, J. S.; Hasenstein, K. H.; Mulkey, T. J.; Yang, R. L.; Evans, M. L.

1990-01-01

We examined the involvement of abscisic acid (ABA) and xanthoxin (Xan) in maize root gravitropism by (1) testing the ability of ABA to allow positive gravitropism in dark-grown seedlings of the maize cultivar LG11, a cultivar known to require light for positive gravitropism of the primary root, (2) comparing curvature in roots in which half of the cap had been excised and replaced with agar containing either ABA or indole-3-acetic acid (IAA), (3) measuring gravitropism in roots of seedlings submerged in oxygenated solutions of ABA or IAA and (4) testing the effect of Xan on root elongation. Using a variety of methods of applying ABA to the root, we found that ABA did not cause horizontally-oriented primary roots of dark-grown seedlings to become positively gravitropic. Replacing half of the root cap of vertically oriented roots with an agar block containing ABA had little or no effect on curvature relative to that of controls in which the half cap was replaced by a plain agar block. Replacement of the removed half cap with IAA either canceled or reversed the curvature displayed by controls. When light-grown seedlings were submerged in ABA they responded strongly to gravistimulation while those in IAA did not. Xan (up to 0.1 mM) did not affect root elongation. The results indicate that ABA is not a likely mediator of root gravitropism and that the putative ABA precursor, Xan, lacks the appropriate growth-inhibiting properties to serve as a mediator of root gravitropism.

Defining the core Arabidopsis thaliana root microbiome

PubMed Central

Gehring, Jase; Malfatti, Stephanie; Tremblay, Julien; Engelbrektson, Anna; Kunin, Victor; del Rio, Tijana Glavina; Edgar, Robert C.; Eickhorst, Thilo; Ley, Ruth E.; Hugenholtz, Philip; Tringe, Susannah Green; Dangl, Jeffery L.

2014-01-01

Land plants associate with a root microbiota distinct from the complex microbial community present in surrounding soil. The microbiota colonizing therhizosphere(immediately surroundingthe root) and the endophytic compartment (within the root) contribute to plant growth, productivity, carbon sequestration and phytoremediation1-3. Colonization of the root occurs despite a sophisticated plant immune system4,5, suggesting finely tuned discrimination of mutualists and commensals from pathogens. Genetic principles governing the derivation of host-specific endophyte communities from soil communities are poorly understood. Here we report the pyrosequencing of the bacterial 16S ribosomal RNA gene of more than 600 Arabidopsis thaliana plants to test the hypotheses that the root rhizosphere and endophytic compartment microbiota of plants grown under controlled conditions in natural soils are sufficiently dependent on the host to remain consistent across different soil types and developmental stages, and sufficiently dependent on host genotype to vary between inbred Arabidopsis accessions. We describe different bacterial communities in two geochemically distinct bulk soils and in rhizosphere and endophytic compartments prepared from roots grown in these soils. The communities in each compartment are strongly influenced by soil type. Endophytic compartments from both soils feature overlapping, low-complexity communities that are markedly enriched in Actinobacteria and specific families from other phyla, notably Proteobacteria. Some bacteria vary quantitatively between plants of different developmental stage and genotype. Our rigorous definition of an endophytic compartment microbiome should facilitate controlled dissection of plantmicrobe interactions derived from complex soil communities. PMID:22859206

Kinetic features of gravicurvature of pea (Pisum sativum) and cress (Lepidium sativum) roots

NASA Astrophysics Data System (ADS)

Polishchuk, O. V.

The upper sides of roots oriented horizontally grow more rapidly than the lower sides, causing the root ultimately to grow downward; this phenomenon is known as positive gravitropism. This ability is based on implicit mechanism which is being extensively investigated. Elaborate analysis of kinetic features of gravicurvature may complement the investigation. Pea and cress roots have positive gravitropism as roots of majority of higher plants. Mainly we investigated dependence of gravicurvature angle on time of gravistimulation. Two-day-old seedlings of cress (Lepidium sativum L. cv. P896) and four-day-old pea ones (Pisum sativum L. cv. Damir-2) were placed on 1% agar medium in Petri dishes and turned on angle of gravistimulation. Then they were photographed at the same position each hour of gravistimulation. Photographs were analyzed with the help of Image Tool software program. Both pea and cress roots showed two phases of gravitropic response during gravistimulation for 6 hours when the initial angle of gravistimulation was 135 degrees. Two peaks of the rate of bending were observed. In cress roots, the first peak was much lower and the distance between the two peaks was greater than in pea roots. Curves of gravitropic bending of cress roots grown in agar had one or two inflections while in the case of roots grown on filter paper curves had no inflections. These data are in agreement with the effect of the external medium on the gravitropic curvature of rice roots reported by Staves et al. (1997). Our results may reflect the fact that at least two systems that contribute to gravicurvature may exist in roots. These systems may be ligand-receptor complexes that may be formed with different kinetics in two different regions of the root. The most probable ligand is auxin and the regions appear to be central elongation zone (CEZ) and distal elongation zone (DEZ), that were reported to be centers of tropic bending in roots. Thus, dependence of rate of root bending on time may represent a superposition of at least two constituents. Moreover, differences in kinetics of bending between pea and cress roots may correspond to different kinetic parameters and contribution of the constituents. (Financial support by STCU: NN-13R).

Whole plant acclimation responses by finger millet to low nitrogen stress.

PubMed

Goron, Travis L; Bhosekar, Vijay K; Shearer, Charles R; Watts, Sophia; Raizada, Manish N

2015-01-01

The small grain cereal, finger millet (FM, Eleusine coracana L. Gaertn), is valued by subsistence farmers in India and East Africa as a low-input crop. It is reported by farmers to require no added nitrogen (N), or only residual N, to produce grain. Exact mechanisms underlying the acclimation responses of FM to low N are largely unknown, both above and below ground. In particular, the responses of FM roots and root hairs to N or any other nutrient have not previously been reported. Given its low N requirement, FM also provides a rare opportunity to study long-term responses to N starvation in a cereal species. The objective of this study was to survey the shoot and root morphometric responses of FM, including root hairs, to low N stress. Plants were grown in pails in a semi-hydroponic system on clay containing extremely low background N, supplemented with N or no N. To our surprise, plants grown without deliberately added N grew to maturity, looked relatively normal and produced healthy seed heads. Plants responded to the low N treatment by decreasing shoot, root, and seed head biomass. These declines under low N were associated with decreased shoot tiller number, crown root number, total crown root length and total lateral root length, but with no consistent changes in root hair traits. Changes in tiller and crown root number appeared to coordinate the above and below ground acclimation responses to N. We discuss the remarkable ability of FM to grow to maturity without deliberately added N. The results suggest that FM should be further explored to understand this trait. Our observations are consistent with indigenous knowledge from subsistence farmers in Africa and Asia, where it is reported that this crop can survive extreme environments.

Influence of arbuscular mycorrhizae on the root system of maize plants under salt stress.

PubMed

Sheng, Min; Tang, Ming; Chen, Hui; Yang, Baowei; Zhang, Fengfeng; Huang, Yanhui

2009-07-01

Salt stress has become a severe global problem, and salinity is one of the most important abiotic factors limiting plant growth and yield. It is known that arbuscular mycorrhizal (AM) fungi decrease plant yield losses under salinity. With the aim of determining whether AM inoculation would give an advantage to root development under salt stress, a greenhouse experiment was carried out with AM or without AM fungi. Maize plants were grown in a sand and soil mixture with 5 NaCl levels (0, 0.5, 1.0, 1.5, and 2.0 g/kg dry substrate) for 55 days, following 15 days of nonsaline pretreatment. At all salt levels, mycorrhizal plants had higher dry shoot and root mass, higher root activity, and lower root to shoot ratios than non-mycorrhizal plants. In salt-free soil, root length, root surface area, root volume, and number of root tips and forks were significantly larger in mycorrhizal plants than in non-mycorrhizal plants, whereas, under salt stress, average root diameter and root volume of mycorrhizal plants were larger than those of non-mycorrhizal plants. Regardless of the NaCl level, mycorrhizal plants had lower specific root length, lower percentage of root length in the 0-0.2 mm diameter class, and higher percentage of root length in both the 0.2-0.4 mm and 0.4-0.6 mm diameter classes, which suggests that the root system shows a significant shift towards a thicker root system when maize plants were inoculated with Glomus mosseae (Nicolson & Gerdemann). The results presented here indicate that the improvements in root activity and the coarse root system of mycorrhizal maize may help in alleviating salt stress on the plant.

Influence of microgravity on root-cap regeneration and the structure of columella cells in Zea mays

NASA Technical Reports Server (NTRS)

Moore, R.; McClelen, C. E.; Fondren, W. M.; Wang, C. L.

1987-01-01

We launched imbibed seeds and seedlings of Zea mays into outer space aboard the space shuttle Columbia to determine the influence of microgravity on 1) root-cap regeneration, and 2) the distribution of amyloplasts and endoplasmic reticulum (ER) in the putative statocytes (i.e., columella cells) of roots. Decapped roots grown on Earth completely regenerated their caps within 4.8 days after decapping, while those grown in microgravity did not regenerate caps. In Earth-grown seedlings, the ER was localized primarily along the periphery of columella cells, and amyloplasts sedimented in response to gravity to the lower sides of the cells. Seeds germinated on Earth and subsequently launched into outer space had a distribution of ER in columella cells similar to that of Earth-grown controls, but amyloplasts were distributed throughout the cells. Seeds germinated in outer space were characterized by the presence of spherical and ellipsoidal masses of ER and randomly distributed amyloplasts in their columella cells. These results indicate that 1) gravity is necessary for regeneration of the root cap, 2) columella cells can maintain their characteristic distribution of ER in microgravity only if they are exposed previously to gravity, and 3) gravity is necessary to distribute the ER in columella cells of this cultivar of Z. mays.

A split-root technique for measuring root water potential.

PubMed

Adeoye, K B; Rawlins, S L

1981-07-01

Water encounters various resistances in moving along a path of decreasing potential energy from the soil through the plant to the atmosphere. The reported relative magnitudes of these pathway resistances vary widely and often these results are conflicting. One reason for such inconsistency is the difficulty in measuring the potential drop across various segments of the soil-plant-atmosphere continuum. The measurement of water potentials at the soil-root interface and in the root xylem of a transpiring plant remains a challenging problem.In the divided root experiment reported here, the measured water potential of an enclosed, nonabsorbing branch of the root system of young corn (Bonanza) plants to infer the water potential of the remaining roots growing in soil was used. The selected root branch of the seedling was grown in a specially constructed Teflon test tube into which a screen-enclosed thermocouple psychrometer was inserted and sealed to monitor the root's water potential. The root and its surrounding atmosphere were assumed to be in vapor equilibrium.

A Split-Root Technique for Measuring Root Water Potential

PubMed Central

Adeoye, Kingsley B.; Rawlins, Stephen L.

1981-01-01

Water encounters various resistances in moving along a path of decreasing potential energy from the soil through the plant to the atmosphere. The reported relative magnitudes of these pathway resistances vary widely and often these results are conflicting. One reason for such inconsistency is the difficulty in measuring the potential drop across various segments of the soil-plant-atmosphere continuum. The measurement of water potentials at the soil-root interface and in the root xylem of a transpiring plant remains a challenging problem. In the divided root experiment reported here, the measured water potential of an enclosed, nonabsorbing branch of the root system of young corn (Bonanza) plants to infer the water potential of the remaining roots growing in soil was used. The selected root branch of the seedling was grown in a specially constructed Teflon test tube into which a screen-enclosed thermocouple psychrometer was inserted and sealed to monitor the root's water potential. The root and its surrounding atmosphere were assumed to be in vapor equilibrium. Images PMID:16661886

Microgravity Effects on Water Supply and Substrate Properties in Porous Matrix Root Support Systems

NASA Astrophysics Data System (ADS)

Bingham, G. E.; Jones, S. B.; Or, D.; Podolski, I. G.; Levinskikh, M. A.; Sytchov, V. N.; Ivanova, T.; Kostov, P.; Sapunova, S.; Dandolov, I.; Bubenheim, D. B.; Jahns, G.

2000-12-01

The control of water content and water movement in granular substrate-based plant root systems in microgravity is a complex problem. Improper water and oxygen delivery to plant roots has delayed studies of the effects of microgravity on plant development and the use of plants in physical and mental life support systems. Our international effort (USA, Russia and Bulgaria) has upgraded the plant growth facilities on the Mir Orbital Station (OS) and used them to study the full life cycle of plants. The Bulgarian-Russian-developed Svet Space Greenhouse (SG) system was upgraded on the Mir OS in 1996. The US developed Gas Exchange Measurement System (GEMS) greatly extends the range of environmental parameters monitored. The Svet-GEMS complex was used to grow a fully developed wheat crop during 1996. The growth rate and development of these plants compared well with earth grown plants indicating that the root zone water and oxygen stresses that have limited plant development in previous long-duration experiments have been overcome. However, management of the root environment during this experiment involved several significant changes in control settings as the relationship between the water delivery system, water status sensors, and the substrate changed during the growth cycles.

Factors influencing real time internal structural visualization and dynamic process monitoring in plants using synchrotron-based phase contrast X-ray imaging

PubMed Central

Karunakaran, Chithra; Lahlali, Rachid; Zhu, Ning; Webb, Adam M.; Schmidt, Marina; Fransishyn, Kyle; Belev, George; Wysokinski, Tomasz; Olson, Jeremy; Cooper, David M. L.; Hallin, Emil

2015-01-01

Minimally invasive investigation of plant parts (root, stem, leaves, and flower) has good potential to elucidate the dynamics of plant growth, morphology, physiology, and root-rhizosphere interactions. Laboratory based absorption X-ray imaging and computed tomography (CT) systems are extensively used for in situ feasibility studies of plants grown in natural and artificial soil. These techniques have challenges such as low contrast between soil pore space and roots, long X-ray imaging time, and low spatial resolution. In this study, the use of synchrotron (SR) based phase contrast X-ray imaging (PCI) has been demonstrated as a minimally invasive technique for imaging plants. Above ground plant parts and roots of 10 day old canola and wheat seedlings grown in sandy clay loam soil were successfully scanned and reconstructed. Results confirmed that SR-PCI can deliver good quality images to study dynamic and real time processes such as cavitation and water-refilling in plants. The advantages of SR-PCI, effect of X-ray energy, and effective pixel size to study plant samples have been demonstrated. The use of contrast agents to monitor physiological processes in plants was also investigated and discussed. PMID:26183486

The Signal Transducer NPH3 Integrates the Phototropin1 Photosensor with PIN2-Based Polar Auxin Transport in Arabidopsis Root Phototropism[C][W

PubMed Central

Wan, Yinglang; Jasik, Jan; Wang, Li; Hao, Huaiqing; Volkmann, Dieter; Menzel, Diedrik; Mancuso, Stefano; Baluška, František; Lin, Jinxing

2012-01-01

Under blue light (BL) illumination, Arabidopsis thaliana roots grow away from the light source, showing a negative phototropic response. However, the mechanism of root phototropism is still unclear. Using a noninvasive microelectrode system, we showed that the BL sensor phototropin1 (phot1), the signal transducer NONPHOTOTROPIC HYPOCOTYL3 (NPH3), and the auxin efflux transporter PIN2 were essential for BL-induced auxin flux in the root apex transition zone. We also found that PIN2-green fluorescent protein (GFP) localized to vacuole-like compartments (VLCs) in dark-grown root epidermal and cortical cells, and phot1/NPH3 mediated a BL-initiated pathway that caused PIN2 redistribution to the plasma membrane. When dark-grown roots were exposed to brefeldin A (BFA), PIN2-GFP remained in VLCs in darkness, and BL caused PIN2-GFP disappearance from VLCs and induced PIN2-GFP-FM4-64 colocalization within enlarged compartments. In the nph3 mutant, both dark and BL BFA treatments caused the disappearance of PIN2-GFP from VLCs. However, in the phot1 mutant, PIN2-GFP remained within VLCs under both dark and BL BFA treatments, suggesting that phot1 and NPH3 play different roles in PIN2 localization. In conclusion, BL-induced root phototropism is based on the phot1/NPH3 signaling pathway, which stimulates the shootward auxin flux by modifying the subcellular targeting of PIN2 in the root apex transition zone. PMID:22374399

Production of ajmalicine and ajmaline in hairy root cultures of Rauvolfia micrantha Hook f., a rare and endemic medicinal plant.

PubMed

Sudha, C G; Obul Reddy, B; Ravishankar, G A; Seeni, S

2003-04-01

Hairy roots of Rauvolfia micrantha were induced from hypocotyl explants of 2-3 weeks old aseptic seedlings using Agrobacterium rhizogenes ATCC 15834. Hairy roots grown in half-strength Murashige & Skoog (MS) medium with 0.2 mg indole 3-butyric acid l-1 and 0.1 mg alpha-naphthaleneacetic acid l-1 produced more ajmaline (0.01 mg g-1 dry wt) and ajmalicine (0.006 mg g-1 dry wt) than roots grown in auxin-free medium. Ajmaline (0.003 mg g-1 dry wt) and ajmalicine (0.0007 mg g-1 dry wt) were also produced in normal root cultures. This is the first report of production of ajmaline and ajmalicine in hairy root cultures of Rauvolfia micrantha.

Rabbits and Grasshoppers: Vectors of Endomycorrhizal Fungi on New Coal Mine Spoil

Treesearch

Felix Jr. Ponder

1980-01-01

Rabbit droppings and grasshoppers were collected on recently graded coal mine spoil to determine if they were vectors of endomycorrhizal fingi. After 6 weeks of growth, roots of rye grass and sudan grass grown in mixtures of sterilized sand containing either unsterilized rabbit droppings or grasshoppers were endomycorrhizal, while the roots of plants grown in...

Accumulation of phenanthrene by roots of intact wheat (Triticum acstivnm L.) seedlings: passive or active uptake?

PubMed Central

2010-01-01

Background Polycyclic aromatic hydrocarbons (PAHs) are of particular concern due to their hydrophobic, recalcitrant, persistent, potentially carcinogenic, mutagenic and toxic properties, and their ubiquitous occurrence in the environment. Most of the PAHs in the environment are present in surface soil. Plants grown in PAH-contaminated soils or water can become contaminated with PAHs because of their uptake. Therefore, they may threaten human and animal health. However, the mechanism for PAHs uptake by crop roots is little understood. It is important to understand exactly how PAHs are transported into the plant root system and into the human food chain, since it is beneficial in governing crop contamination by PAHs, remedying soils or waters polluted by PAHs with plants, and modeling potential uptake for risk assessment. Results The possibility that plant roots may take up phenanthrene (PHE), a representative of PAHs, via active process was investigated using intact wheat (Triticum acstivnm L.) seedlings in a series of hydroponic experiments. The time course for PHE uptake into wheat roots grown in Hoagland solution containing 5.62 μM PHE for 36 h could be separated into two periods: a fast uptake process during the initial 2 h and a slow uptake component thereafter. Concentration-dependent PHE uptake was characterized by a smooth, saturable curve with an apparent Km of 23.7 μM and a Vmax of 208 nmol g-1 fresh weight h-1, suggesting a carrier-mediated uptake system. Competition between PHE and naphthalene for their uptake by the roots further supported the carrier-mediated uptake system. Low temperature and 2,4-dinitrophenol (DNP) could inhibit PHE uptake equally, indicating that metabolism plays a role in PHE uptake. The inhibitions by low temperature and DNP were strengthened with increasing concentration of PHE in external solution within PHE water solubility (7.3 μM). The contribution of active uptake to total absorption was almost 40% within PHE water solubility. PHE uptake by wheat roots caused an increase in external solution pH, implying that wheat roots take up PHE via a PHE/nH+ symport system. Conclusion It is concluded that an active, carrier-mediated and energy-consuming influx process is involved in the uptake of PHE by plant roots. PMID:20307286

Prioritizing quantitative trait loci for root system architecture in tetraploid wheat

PubMed Central

Maccaferri, Marco; El-Feki, Walid; Nazemi, Ghasemali; Salvi, Silvio; Canè, Maria Angela; Colalongo, Maria Chiara; Stefanelli, Sandra; Tuberosa, Roberto

2016-01-01

Optimization of root system architecture (RSA) traits is an important objective for modern wheat breeding. Linkage and association mapping for RSA in two recombinant inbred line populations and one association mapping panel of 183 elite durum wheat (Triticum turgidum L. var. durum Desf.) accessions evaluated as seedlings grown on filter paper/polycarbonate screening plates revealed 20 clusters of quantitative trait loci (QTLs) for root length and number, as well as 30 QTLs for root growth angle (RGA). Divergent RGA phenotypes observed by seminal root screening were validated by root phenotyping of field-grown adult plants. QTLs were mapped on a high-density tetraploid consensus map based on transcript-associated Illumina 90K single nucleotide polymorphisms (SNPs) developed for bread and durum wheat, thus allowing for an accurate cross-referencing of RSA QTLs between durum and bread wheat. Among the main QTL clusters for root length and number highlighted in this study, 15 overlapped with QTLs for multiple RSA traits reported in bread wheat, while out of 30 QTLs for RGA, only six showed co-location with previously reported QTLs in wheat. Based on their relative additive effects/significance, allelic distribution in the association mapping panel, and co-location with QTLs for grain weight and grain yield, the RSA QTLs have been prioritized in terms of breeding value. Three major QTL clusters for root length and number (RSA_QTL_cluster_5#, RSA_QTL_cluster_6#, and RSA_QTL_cluster_12#) and nine RGA QTL clusters (QRGA.ubo-2A.1, QRGA.ubo-2A.3, QRGA.ubo-2B.2/2B.3, QRGA.ubo-4B.4, QRGA.ubo-6A.1, QRGA.ubo-6A.2, QRGA.ubo-7A.1, QRGA.ubo-7A.2, and QRGA.ubo-7B) appear particularly valuable for further characterization towards a possible implementation of breeding applications in marker-assisted selection and/or cloning of the causal genes underlying the QTLs. PMID:26880749

Plant density-dependent variations in bioactive markers and root yield in Australian-grown Salvia miltiorrhiza Bunge.

PubMed

Li, Chun Guang; Sheng, Shu Jun; Pang, Edwin C K; May, Brian; Xue, Charlie Chang Li

2011-04-01

The plant density-dependent variations in the root yield and content, and the yield of biomarkers in Australian grown Salvia miltiorrhiza Bunge, a commonly used Chinese medicinal herb for the treatment of cardiovascular diseases, were investigated in a field trial involving six different plant densities. The key biomarker compounds cryptotanshinone, tanshinone I, tanshinone IIA, and salvianolic acid B were quantified by a validated RP-HPLC method, and the root yields were determined per plant pair or unit area. There were significant variations (p<0.05) in the root yields and contents and the yields of the biomarkers between the different plant densities. Positive linear correlations were observed between the contents of the three tanshinones, whereas negative linear correlations were revealed between the contents of the tanshinones and salvianolic acid B. The highest root yield per plant pair was achieved when the plants were grown at 45×30 cm or 45×40 cm, whereas the highest root production par unit area was obtained for a plant density of 30×30 cm. The highest contents of the three tanshinones and the most abundant production of these tanshinones per unit area were achieved when the plants were grown at 30×30 cm. However, the highest content of salvianolic acid B was found for a density of 45×40 cm, while its highest yield per unit area was obtained for densities of 30×40 cm or 45×30 cm. The findings suggest that the plant density distinctly affects the root yield and content and the yield of tanshinones and salvianolic acid B in Australian grown S. miltiorrhiza, which may be used as a guide for developing optimal agricultural procedures for cultivating this herb. Copyright © 2011 Verlag Helvetica Chimica Acta AG, Zürich.

Development of accelerated net nitrate uptake. [Zea mays L

DOE Office of Scientific and Technical Information (OSTI.GOV)

MacKown, C.T.; McClure, P.R.

1988-05-01

Upon initial nitrate exposure, net nitrate uptake rates in roots of a wide variety of plants accelerate within 6 to 8 hours to substantially greater rates. Effects of solution nitrate concentrations and short pulses of nitrate ({le}1 hour) upon nitrate-induced acceleration of nitrate uptake in maize (Zea mays L.) were determined. Root cultures of dark-grown seedlings, grown without nitrate, were exposed to 250 micromolar nitrate for 0.25 to 1 hour or to various solution nitrate concentration (10-250 micromolar) for 1 hour before returning them to a nitrate-free solution. Net nitrate uptake rates were assayed at various periods following nitrate exposuremore » and compared to rates of roots grown either in the absence of nitrate (CaSO{sub 4}-grown) or with continuous nitrate for at least 20 hours. Three hours after initial nitrate exposure, nitrate pulse treatments increased nitrate uptake rates three- to four-fold compared to the rates of CaSO{sub 4}-grown roots. When cycloheximide (5 micrograms per milliliter) was included during a 1-hour pulse with 250 micromolar nitrate, development of the accelerated nitrate uptake state was delayed. Otherwise, nitrate uptake rates reached maximum values within 6 hours before declining. Maximum rates, however, were significantly less than those of roots exposed continuously for 20, 32, or 44 hours. Pulsing for only 0.25 hour with 250 micromolar nitrate and for 1 hour with 10 micromolar caused acceleration of nitrate uptake, but the rates attained were either less than or not sustained for a duration comparable to those of roots pulsed for 1 hour with 250 micromolar nitrate. These results indicate that substantial development of nitrate-induced accelerated nitrate uptake state can be achieved by small endogenous accumulations of nitrate, which appear to moderate the activity or level of root nitrate uptake.« less

Phylogenetically structured traits in root systems influence arbuscular mycorrhizal colonization in woody angiosperms

DOE PAGES

Valverde-Barrantes, Oscar J.; Horning, Amber L.; Smemo, Kurt A.; ...

2016-02-10

In this study, there is little quantitative information about the relationship between root traits and the extent of arbuscular mycorrhizal fungi (AMF) colonization. We expected that ancestral species with thick roots will maximize AMF habitat by maintaining similar root traits across root orders (i.e., high root trait integration), whereas more derived species are expected to display a sharp transition from acquisition to structural roots. Moreover, we hypothesized that interspecific morphological differences rather than soil conditions will be the main driver of AMF colonization We analyzed 14 root morphological and chemical traits and AMF colonization rates for the first three rootmore » orders of 34 temperate tree species grown in two common gardens. We also collected associated soil to measure the effect of soil conditions on AMF colonization Results Thick-root magnoliids showed less variation in root traits along root orders than more-derived angiosperm groups. Variation in stele:root diameter ratio was the best indicator of AMF colonization within and across root orders. Root functional traits rather than soil conditions largely explained the variation in AMF colonization among species. In conclusion, not only the traits of first order but the entire structuring of the root system varied among plant lineages, suggesting alternative evolutionary strategies of resource acquisition. Understanding evolutionary pathways in below ground organs could open new avenues to understand tree species influence on soil carbon and nutrient cycling.« less

Phylogenetically structured traits in root systems influence arbuscular mycorrhizal colonization in woody angiosperms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Valverde-Barrantes, Oscar J.; Horning, Amber L.; Smemo, Kurt A.

In this study, there is little quantitative information about the relationship between root traits and the extent of arbuscular mycorrhizal fungi (AMF) colonization. We expected that ancestral species with thick roots will maximize AMF habitat by maintaining similar root traits across root orders (i.e., high root trait integration), whereas more derived species are expected to display a sharp transition from acquisition to structural roots. Moreover, we hypothesized that interspecific morphological differences rather than soil conditions will be the main driver of AMF colonization We analyzed 14 root morphological and chemical traits and AMF colonization rates for the first three rootmore » orders of 34 temperate tree species grown in two common gardens. We also collected associated soil to measure the effect of soil conditions on AMF colonization Results Thick-root magnoliids showed less variation in root traits along root orders than more-derived angiosperm groups. Variation in stele:root diameter ratio was the best indicator of AMF colonization within and across root orders. Root functional traits rather than soil conditions largely explained the variation in AMF colonization among species. In conclusion, not only the traits of first order but the entire structuring of the root system varied among plant lineages, suggesting alternative evolutionary strategies of resource acquisition. Understanding evolutionary pathways in below ground organs could open new avenues to understand tree species influence on soil carbon and nutrient cycling.« less

Understanding the development of roots exposed to contaminants and the potential of plant-associated bacteria for optimization of growth

PubMed Central

Remans, Tony; Thijs, Sofie; Truyens, Sascha; Weyens, Nele; Schellingen, Kerim; Keunen, Els; Gielen, Heidi; Cuypers, Ann; Vangronsveld, Jaco

2012-01-01

Background and Scope Plant responses to the toxic effects of soil contaminants, such as excess metals or organic substances, have been studied mainly at physiological, biochemical and molecular levels, but the influence on root system architecture has received little attention. Nevertheless, the precise position, morphology and extent of roots can influence contaminant uptake. Here, data are discussed that aim to increase the molecular and ecological understanding of the influence of contaminants on root system architecture. Furthermore, the potential of plant-associated bacteria to influence root growth by their growth-promoting and stress-relieving capacities is explored. Methods Root growth parameters of Arabidopsis thaliana seedlings grown in vertical agar plates are quantified. Mutants are used in a reverse genetics approach to identify molecular components underlying quantitative changes in root architecture after exposure to excess cadmium, copper or zinc. Plant-associated bacteria are isolated from contaminated environments, genotypically and phenotypically characterized, and used to test plant root growth improvement in the presence of contaminants. Key Results The molecular determinants of primary root growth inhibition and effects on lateral root density by cadmium were identified. A vertical split-root system revealed local effects of cadmium and copper on root development. However, systemic effects of zinc exposure on root growth reduced both the avoidance of contaminated areas and colonization of non-contaminated areas. The potential for growth promotion and contaminant degradation of plant-associated bacteria was demonstrated by improved root growth of inoculated plants exposed to 2,4-di-nitro-toluene (DNT) or cadmium. Conclusions Knowledge concerning the specific influence of different contaminants on root system architecture and the molecular mechanisms by which this is achieved can be combined with the exploitation of plant-associated bacteria to influence root development and increase plant stress tolerance, which should lead to more optimal root systems for application in phytoremediation or safer biomass production. PMID:22634257

Understanding the development of roots exposed to contaminants and the potential of plant-associated bacteria for optimization of growth.

PubMed

Remans, Tony; Thijs, Sofie; Truyens, Sascha; Weyens, Nele; Schellingen, Kerim; Keunen, Els; Gielen, Heidi; Cuypers, Ann; Vangronsveld, Jaco

2012-07-01

Plant responses to the toxic effects of soil contaminants, such as excess metals or organic substances, have been studied mainly at physiological, biochemical and molecular levels, but the influence on root system architecture has received little attention. Nevertheless, the precise position, morphology and extent of roots can influence contaminant uptake. Here, data are discussed that aim to increase the molecular and ecological understanding of the influence of contaminants on root system architecture. Furthermore, the potential of plant-associated bacteria to influence root growth by their growth-promoting and stress-relieving capacities is explored. Root growth parameters of Arabidopsis thaliana seedlings grown in vertical agar plates are quantified. Mutants are used in a reverse genetics approach to identify molecular components underlying quantitative changes in root architecture after exposure to excess cadmium, copper or zinc. Plant-associated bacteria are isolated from contaminated environments, genotypically and phenotypically characterized, and used to test plant root growth improvement in the presence of contaminants. The molecular determinants of primary root growth inhibition and effects on lateral root density by cadmium were identified. A vertical split-root system revealed local effects of cadmium and copper on root development. However, systemic effects of zinc exposure on root growth reduced both the avoidance of contaminated areas and colonization of non-contaminated areas. The potential for growth promotion and contaminant degradation of plant-associated bacteria was demonstrated by improved root growth of inoculated plants exposed to 2,4-di-nitro-toluene (DNT) or cadmium. Knowledge concerning the specific influence of different contaminants on root system architecture and the molecular mechanisms by which this is achieved can be combined with the exploitation of plant-associated bacteria to influence root development and increase plant stress tolerance, which should lead to more optimal root systems for application in phytoremediation or safer biomass production.

Deep Phenotyping of Coarse Root Architecture in R. pseudoacacia Reveals That Tree Root System Plasticity Is Confined within Its Architectural Model

PubMed Central

Danjon, Frédéric; Khuder, Hayfa; Stokes, Alexia

2013-01-01

This study aims at assessing the influence of slope angle and multi-directional flexing and their interaction on the root architecture of Robinia pseudoacacia seedlings, with a particular focus on architectural model and trait plasticity. 36 trees were grown from seed in containers inclined at 0° (control) or 45° (slope) in a glasshouse. The shoots of half the plants were gently flexed for 5 minutes a day. After 6 months, root systems were excavated and digitized in 3D, and biomass measured. Over 100 root architectural traits were determined. Both slope and flexing increased significantly plant size. Non-flexed trees on 45° slopes developed shallow roots which were largely aligned perpendicular to the slope. Compared to the controls, flexed trees on 0° slopes possessed a shorter and thicker taproot held in place by regularly distributed long and thin lateral roots. Flexed trees on the 45° slope also developed a thick vertically aligned taproot, with more volume allocated to upslope surface lateral roots, due to the greater soil volume uphill. We show that there is an inherent root system architectural model, but that a certain number of traits are highly plastic. This plasticity will permit root architectural design to be modified depending on external mechanical signals perceived by young trees. PMID:24386227

Sorghum root-system classification in contrasting P environments reveals three main rooting types and root-architecture-related marker-trait associations.

PubMed

Parra-Londono, Sebastian; Kavka, Mareike; Samans, Birgit; Snowdon, Rod; Wieckhorst, Silke; Uptmoor, Ralf

2018-02-12

Roots facilitate acquisition of macro- and micronutrients, which are crucial for plant productivity and anchorage in the soil. Phosphorus (P) is rapidly immobilized in the soil and hardly available for plants. Adaptation to P scarcity relies on changes in root morphology towards rooting systems well suited for topsoil foraging. Root-system architecture (RSA) defines the spatial organization of the network comprising primary, lateral and stem-derived roots and is important for adaptation to stress conditions. RSA phenotyping is a challenging task and essential for understanding root development. In this study, 19 traits describing RSA were analysed in a diversity panel comprising 194 sorghum genotypes, fingerprinted with a 90-k single-nucleotide polymorphism (SNP) array and grown under low and high P availability. Multivariate analysis was conducted and revealed three different RSA types: (1) a small root system; (2) a compact and bushy rooting type; and (3) an exploratory root system, which might benefit plant growth and development if water, nitrogen (N) or P availability is limited. While several genotypes displayed similar rooting types in different environments, others responded to P scarcity positively by developing more exploratory root systems, or negatively with root growth suppression. Genome-wide association studies revealed significant quantitative trait loci (P < 2.9 × 10-6) on chromosomes SBI-02, SBI-03, SBI-05 and SBI-09. Co-localization of significant and suggestive (P < 5.7 × 10-5) associations for several traits indicated hotspots controlling root-system development on chromosomes SBI-02 and SBI-03. Sorghum genotypes with a compact, bushy and shallow root system provide potential adaptation to P scarcity in the field by allowing thorough topsoil foraging, while genotypes with an exploratory root system may be advantageous if N or water is the limiting factor, although such genotypes showed highest P uptake levels under the artificial conditions of the present study. © The Author(s) 2018. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

The Essential Oils of Rhaponticum carthamoides Hairy Roots and Roots of Soil-Grown Plants: Chemical Composition and Antimicrobial, Anti-Inflammatory, and Antioxidant Activities.

PubMed

Skała, Ewa; Rijo, Patrícia; Garcia, Catarina; Sitarek, Przemysław; Kalemba, Danuta; Toma, Monika; Szemraj, Janusz; Pytel, Dariusz; Wysokińska, Halina; Śliwiński, Tomasz

2016-01-01

The essential oils were isolated by hydrodistillation from the hairy roots (HR) and roots of soil-grown plants (SGR) of Rhaponticum carthamoides and were analyzed by GC-MS method. In the both essential oils 62 compounds were identified. The root essential oils showed the differences in the qualitative and quantitative composition. The sesquiterpene hydrocarbons (55-62%) dominated in both essential oils. The major compounds of HR essential oil were cyperene, 13-norcypera-1(5),11(12)-diene, and cadalene while aplotaxene, nardosina-1(10),11-diene, and dauca-4(11),8-diene dominated in SGR essential oil. Both essential oils showed antibacterial activity especially against Enterococcus faecalis (ATCC 29212) and Pseudomonas aeruginosa (ATCC 27853) (MIC value = 125  µ g/mL). HR and SGR essential oils also decreased the expression of IL-1 β , IL-6, and TNF- α and the ROS level in LPS-treatment astrocytes. This is the first report to describe the chemical composition of R. carthamoides essential oil from hairy roots, its protective effect against LPS-induced inflammation and ROS production in astrocytes, and its antimicrobial potential. The results show that R. carthamoides hairy roots may be a valuable source of the essential oil and may be an alternative to the roots of soil-grown plants.

The Essential Oils of Rhaponticum carthamoides Hairy Roots and Roots of Soil-Grown Plants: Chemical Composition and Antimicrobial, Anti-Inflammatory, and Antioxidant Activities

PubMed Central

Rijo, Patrícia; Garcia, Catarina; Kalemba, Danuta; Toma, Monika; Szemraj, Janusz; Pytel, Dariusz; Śliwiński, Tomasz

2016-01-01

The essential oils were isolated by hydrodistillation from the hairy roots (HR) and roots of soil-grown plants (SGR) of Rhaponticum carthamoides and were analyzed by GC-MS method. In the both essential oils 62 compounds were identified. The root essential oils showed the differences in the qualitative and quantitative composition. The sesquiterpene hydrocarbons (55–62%) dominated in both essential oils. The major compounds of HR essential oil were cyperene, 13-norcypera-1(5),11(12)-diene, and cadalene while aplotaxene, nardosina-1(10),11-diene, and dauca-4(11),8-diene dominated in SGR essential oil. Both essential oils showed antibacterial activity especially against Enterococcus faecalis (ATCC 29212) and Pseudomonas aeruginosa (ATCC 27853) (MIC value = 125 µg/mL). HR and SGR essential oils also decreased the expression of IL-1β, IL-6, and TNF-α and the ROS level in LPS-treatment astrocytes. This is the first report to describe the chemical composition of R. carthamoides essential oil from hairy roots, its protective effect against LPS-induced inflammation and ROS production in astrocytes, and its antimicrobial potential. The results show that R. carthamoides hairy roots may be a valuable source of the essential oil and may be an alternative to the roots of soil-grown plants. PMID:28074117

Establishment of Hairy Root Cultures of Rhaponticum carthamoides (Willd.) Iljin for the Production of Biomass and Caffeic Acid Derivatives

PubMed Central

Skała, Ewa; Kicel, Agnieszka; Olszewska, Monika A.; Kiss, Anna K.

2015-01-01

The aim of the study was to obtain transformed roots of Rhaponticum carthamoides and evaluate their phytochemical profile. Hairy roots were induced from leaf explants by the transformation of Agrobacterium rhizogenes strains A4 and ATCC 15834. The best response (43%) was achieved by infection with A4 strain. The effects of different liquid media (WPM, B5, SH) with full and half-strength concentrations of macro- and micronutrients on biomass accumulation of the best grown hairy root line (RC3) at two different lighting conditions (light or dark) were investigated. The highest biomass (93 g L−1 of the fresh weight after 35 days) was obtained in WPM medium under periodic light. UPLC-PDA-ESI-MS3 and HPLC-PDA analyses of 80% aqueous methanol extracts from the obtained hairy roots revealed the presence of eleven caffeoylquinic acids and their derivatives and five flavonoid glycosides. The production of caffeoylquinic acids and their derivatives was elevated in hairy roots grown in the light. Only light-grown hairy roots demonstrated the capability for the biosynthesis of such flavonoid glycosides as quercetagetin, quercetin, luteolin, and patuletin hexosides. Chlorogenic acid, 3,5-di-O-caffeoylquinic acid and a tentatively identified tricaffeoylquinic acid derivative were detected as the major compounds present in the transformed roots. PMID:25811023

Influence of CO2 change during 90-day experiment on growth characteristics and photosynthetic activity in vegetables grown in Lunar Palace 1

NASA Astrophysics Data System (ADS)

Shao, Lingzhi; Liu, Hong; Wang, Minjuan; Fu, Yuming; Dong, Chen; Liu, Guanghui

To establish bioregenerative life support system (BLSS) on lunar or Mars bases in the future, it is necessary to firstly conduct manned simulation experiments on the ground. For this purpose, Lunar palace 1 as an integrative experimental facility for permanent astrobase life support artificial closed ecosystem was set up, and 90-day experiment was carried out in this system. Vegtables as one of the important plant units, provide various nutrient content for crews in the system, such as vitamin, antioxidants and so on. However, it is not clear yet that how the CO _{2} change during 90-day experiment to affect on growth characteristics and photosynthetic activity in vegtables grown in the system. In this study, red lettuce, red rape, romaine lettuce, and bibb lettuce grown in the system were chosen as the subject investigated. Growth, expressed as dry weight, length of shoot and root, leaf area, was mearsured, and photosynthesis,expressed as net photosynthetic rate, intercellular CO _{2} concentration, chlorophyll contents and fluorescence was analyzed to detemind influence of CO _{2} change during 90-day experiment on growth in vegtables grown in the system.

Phosphate absorption by air-stressed root systems.

PubMed

Dove, L D

1969-03-01

Root systems from plants grown in nutrient solution were exposed to air and either transferred to fresh nutrient solution containing (32)P-labeled phosphate or placed in a psychrometer to determine their water potential. The amount of (32)P absorbed by maize and soybean roots in the hour following their exposure to air was proportional to their water potential at the time they were transferred. Some cells, probably located in the stele, were more resistant to moisture stress than others. Absorption of (32)P by all cells was severely inhibited by water potentials below-12 to-15 bars. Nearly normal amounts of the radioisotope and total phosphate were absorbed within 72 hr following root exposure of 4 of 5 species of detopped plants; some phosphorus was lost to the nutrient solution. Uptake of (32)P by passive processes was increased slightly by exposure of roots of intact maize plants to air, but the increase did not compensate for the substantial reduction in actively-absorbed (32)P.

Descendant root volume varies as a function of root type: estimation of root biomass lost during uprooting in Pinus pinaster.

PubMed

Danjon, Frédéric; Caplan, Joshua S; Fortin, Mathieu; Meredieu, Céline

2013-01-01

Root systems of woody plants generally display a strong relationship between the cross-sectional area or cross-sectional diameter (CSD) of a root and the dry weight of biomass (DWd) or root volume (Vd) that has grown (i.e., is descendent) from a point. Specification of this relationship allows one to quantify root architectural patterns and estimate the amount of material lost when root systems are extracted from the soil. However, specifications of this relationship generally do not account for the fact that root systems are comprised of multiple types of roots. We assessed whether the relationship between CSD and Vd varies as a function of root type. Additionally, we sought to identify a more accurate and time-efficient method for estimating missing root volume than is currently available. We used a database that described the 3D root architecture of Pinus pinaster root systems (5, 12, or 19 years) from a stand in southwest France. We determined the relationship between CSD and Vd for 10,000 root segments from intact root branches. Models were specified that did and did not account for root type. The relationships were then applied to the diameters of 11,000 broken root ends to estimate the volume of missing roots. CSD was nearly linearly related to the square root of Vd, but the slope of the curve varied greatly as a function of root type. Sinkers and deep roots tapered rapidly, as they were limited by available soil depth. Distal shallow roots tapered gradually, as they were less limited spatially. We estimated that younger trees lost an average of 17% of root volume when excavated, while older trees lost 4%. Missing volumes were smallest in the central parts of root systems and largest in distal shallow roots. The slopes of the curves for each root type are synthetic parameters that account for differentiation due to genetics, soil properties, or mechanical stimuli. Accounting for this differentiation is critical to estimating root loss accurately.

Descendant root volume varies as a function of root type: estimation of root biomass lost during uprooting in Pinus pinaster

PubMed Central

Danjon, Frédéric; Caplan, Joshua S.; Fortin, Mathieu; Meredieu, Céline

2013-01-01

Root systems of woody plants generally display a strong relationship between the cross-sectional area or cross-sectional diameter (CSD) of a root and the dry weight of biomass (DWd) or root volume (Vd) that has grown (i.e., is descendent) from a point. Specification of this relationship allows one to quantify root architectural patterns and estimate the amount of material lost when root systems are extracted from the soil. However, specifications of this relationship generally do not account for the fact that root systems are comprised of multiple types of roots. We assessed whether the relationship between CSD and Vd varies as a function of root type. Additionally, we sought to identify a more accurate and time-efficient method for estimating missing root volume than is currently available. We used a database that described the 3D root architecture of Pinus pinaster root systems (5, 12, or 19 years) from a stand in southwest France. We determined the relationship between CSD and Vd for 10,000 root segments from intact root branches. Models were specified that did and did not account for root type. The relationships were then applied to the diameters of 11,000 broken root ends to estimate the volume of missing roots. CSD was nearly linearly related to the square root of Vd, but the slope of the curve varied greatly as a function of root type. Sinkers and deep roots tapered rapidly, as they were limited by available soil depth. Distal shallow roots tapered gradually, as they were less limited spatially. We estimated that younger trees lost an average of 17% of root volume when excavated, while older trees lost 4%. Missing volumes were smallest in the central parts of root systems and largest in distal shallow roots. The slopes of the curves for each root type are synthetic parameters that account for differentiation due to genetics, soil properties, or mechanical stimuli. Accounting for this differentiation is critical to estimating root loss accurately. PMID:24167506

Effect of bacterial root symbiosis and urea as source of nitrogen on performance of soybean plants grown hydroponically for Bioregenerative Life Support Systems (BLSSs)

PubMed Central

Paradiso, Roberta; Buonomo, Roberta; Dixon, Mike A.; Barbieri, Giancarlo; De Pascale, Stefania

2015-01-01

Soybean is traditionally grown in soil, where root symbiosis with Bradyrhizobium japonicum can supply nitrogen (N), by means of bacterial fixation of atmospheric N2. Nitrogen fertilizers inhibit N-fixing bacteria. However, urea is profitably used in soybean cultivation in soil, where urease enzymes of telluric microbes catalyze the hydrolysis to ammonium, which has a lighter inhibitory effect compared to nitrate. Previous researches demonstrated that soybean can be grown hydroponically with recirculating complete nitrate-based nutrient solutions. In Space, urea derived from crew urine could be used as N source, with positive effects in resource procurement and waste recycling. However, whether the plants are able to use urea as the sole source of N and its effect on root symbiosis with B. japonicum is still unclear in hydroponics. We compared the effect of two N sources, nitrate and urea, on plant growth and physiology, and seed yield and quality of soybean grown in closed-loop Nutrient Film Technique (NFT) in growth chamber, with or without inoculation with B. japonicum. Urea limited plant growth and seed yield compared to nitrate by determining nutrient deficiency, due to its low utilization efficiency in the early developmental stages, and reduced nutrients uptake (K, Ca, and Mg) throughout the whole growing cycle. Root inoculation with B. japonicum did not improve plant performance, regardless of the N source. Specifically, nodulation increased under fertigation with urea compared to nitrate, but this effect did not result in higher leaf N content and better biomass and seed production. Urea was not suitable as sole N source for soybean in closed-loop NFT. However, the ability to use urea increased from young to adult plants, suggesting the possibility to apply it during reproductive phase or in combination with nitrate in earlier developmental stages. Root symbiosis did not contribute significantly to N nutrition and did not enhance the plant ability to use urea, possibly because of ineffective infection process and nodule functioning in hydroponics. PMID:26579144

Growth and development of Arabidopsis in the Advanced Biological Research System (ABRS) hardware designed for the International Space Station

NASA Astrophysics Data System (ADS)

Savidge, Rodney

Wild type (Col 0) Arabidopsis thaliana were grown in a growth chamber within the single mid-deck sized Advanced Biological Research System (ABRS) spaceflight hardware developed by NASA Kennedy Space Center. Before beginning this experiment, the plants, each rooted in individual transferable tubes containing nutrients, were cultivated hydroponically on halfstrength Hoagland's solution beneath either LED lighting similar to that provided by the ABRS growth chamber or white fluorescent lighting. The leaves of the basal whorl of plants pre-grown in ABRS lighting were small and purplish at the start of the experiment, whereas those under fluorescent lighting were larger and green. The plants were transferred to the ABRS soon after their inflorescence axes had started to elongate, and thereafter they were maintained under preset conditions (22 o C, approximately 1500 ppm CO2 , predominantly 125 µmol m-2 s-1 PAR) with pulses of water provided at 1-3 d intervals (as needed) to the module into which the root tubes were inserted. That module was pre-treated with half-strength Hoagland's nutrient solution on day 0, but no additional nutrients were provided the plants thereafter. Strong primary growth of all inflorescence stems occurred soon after initiating the ABRS experiment, and the plants began forming an overarching canopy of flowering stems beneath the LED lighting module within two weeks. After 38 days the root module was littered with seeds, siliques and abscised leaves, but all plants remained alive. Plants pre-grown in ABRS lighting were more advanced toward senescence, and leaves and stems of plants pre-grown in fluorescent lighting although greener were also acquiring a purplish hue. Microscopy revealed that the flowering stems achieved no secondary growth; however, progressive inward conversion of pith parenchyma into sclerenchyma cells did occur resulting in the inflorescence stems becoming abnormally woody.

Resistance Responses of Potato to Vesicular-Arbuscular Mycorrhizal Fungi under Varying Abiotic Phosphorus Levels.

PubMed

McArthur, D A; Knowles, N R

1992-09-01

In mycorrhizal symbioses, susceptibility of a host plant to infection by fungi is influenced by environmental factors, especially the availability of soil phosphorus. This study describes morphological and biochemical details of interactions between a vesicular-arbuscular mycorrhizal (VAM) fungus and potato (Solanum tuberosum L. cv Russet Burbank) plants, with a particular focus on the physiological basis for P-induced resistance of roots to infection. Root infection by the VAM fungus Glomus fasciculatum ([Thaxt. sensu Gerdemann] Gerdemann and Trappe) was extensive for plants grown with low abiotic P supply, and plant biomass accumulation was enhanced by the symbiosis. The capacity of excised roots from P-deficient plants to produce ethylene in the presence or absence of exogenous 1-amino cyclopropane-1-carboxylic acid (ACC) was markedly reduced by VAM infection. This apparent inhibition of ACC oxidase (ACC(ox)) activity was localized to areas containing infected roots, as demonstrated in split-root studies. Furthermore, leachate from VAM roots contained a potent water-soluble inhibitor of ethylene generation from exogenous ACC by nonmycorrhizal (NM) roots. The leachate from VAM-infected roots had a higher concentration of phenolics, relative to that from NM roots. Moreover, the rates of ethylene formation and phenolic concentration in leachates from VAM roots were inversely correlated, suggesting that this inhibitor may be of a phenolic nature. The specific activity of extracellular peroxidase recovered in root leachates was not stimulated by VAM infection, although activity on a fresh weight basis was significantly enhanced, reflecting the fact that VAM roots had higher protein content than NM roots. Polyphenol oxidase activity of roots did not differ between NM and VAM roots. These results characterize the low resistance response of P-deficient plants to VAM infection. When plants were grown with higher abiotic P supply, the relative benefit of the VAM symbiosis to plant growth decreased and root infection was lower. The in vivo ACC(ox) activity was also greater in roots of plants grown on high levels of P compared with those grown on low levels, although the influence of VAM infection was partially to counteract the nutritional effect of P on ACC(ox) activity. Similar to ACC(ox) activity, extracellular peroxidase activity of roots increased linearly with increasing abiotic P supply, thus indicating a greater potential for resistance to VAM infection. These findings suggest that VAM fungi may alter phenolic metabolism of roots so as to hinder ethylene production and the root's ability to invoke a defense response. Raising the abiotic P supply to plants at least partially restores the capacity of roots to produce ethylene and may, in this way, increase the root's resistance to VAM infection.

Resistance Responses of Potato to Vesicular-Arbuscular Mycorrhizal Fungi under Varying Abiotic Phosphorus Levels 1

PubMed Central

McArthur, David A. J.; Knowles, N. Richard

1992-01-01

In mycorrhizal symbioses, susceptibility of a host plant to infection by fungi is influenced by environmental factors, especially the availability of soil phosphorus. This study describes morphological and biochemical details of interactions between a vesicular-arbuscular mycorrhizal (VAM) fungus and potato (Solanum tuberosum L. cv Russet Burbank) plants, with a particular focus on the physiological basis for P-induced resistance of roots to infection. Root infection by the VAM fungus Glomus fasciculatum ([Thaxt. sensu Gerdemann] Gerdemann and Trappe) was extensive for plants grown with low abiotic P supply, and plant biomass accumulation was enhanced by the symbiosis. The capacity of excised roots from P-deficient plants to produce ethylene in the presence or absence of exogenous 1-amino cyclopropane-1-carboxylic acid (ACC) was markedly reduced by VAM infection. This apparent inhibition of ACC oxidase (ACCox) activity was localized to areas containing infected roots, as demonstrated in split-root studies. Furthermore, leachate from VAM roots contained a potent water-soluble inhibitor of ethylene generation from exogenous ACC by nonmycorrhizal (NM) roots. The leachate from VAM-infected roots had a higher concentration of phenolics, relative to that from NM roots. Moreover, the rates of ethylene formation and phenolic concentration in leachates from VAM roots were inversely correlated, suggesting that this inhibitor may be of a phenolic nature. The specific activity of extracellular peroxidase recovered in root leachates was not stimulated by VAM infection, although activity on a fresh weight basis was significantly enhanced, reflecting the fact that VAM roots had higher protein content than NM roots. Polyphenol oxidase activity of roots did not differ between NM and VAM roots. These results characterize the low resistance response of P-deficient plants to VAM infection. When plants were grown with higher abiotic P supply, the relative benefit of the VAM symbiosis to plant growth decreased and root infection was lower. The in vivo ACCox activity was also greater in roots of plants grown on high levels of P compared with those grown on low levels, although the influence of VAM infection was partially to counteract the nutritional effect of P on ACCox activity. Similar to ACCox activity, extracellular peroxidase activity of roots increased linearly with increasing abiotic P supply, thus indicating a greater potential for resistance to VAM infection. These findings suggest that VAM fungi may alter phenolic metabolism of roots so as to hinder ethylene production and the root's ability to invoke a defense response. Raising the abiotic P supply to plants at least partially restores the capacity of roots to produce ethylene and may, in this way, increase the root's resistance to VAM infection. Images Figure 1 PMID:16652967

The effect of a microgravity (space) environment on the expression of expansins from the peg and root tissues of Cucumis sativus

NASA Technical Reports Server (NTRS)

Link, B. M.; Wagner, E. R.; Cosgrove, D. J.

2001-01-01

In young cucumber seedlings, the peg is a polar outgrowth of tissue that functions by snagging the seed coat, thereby freeing the cotyledons. The development of the peg is thought to be gravity-dependent and has become a model system for plant-gravity response. Peg development requires rapid cell expansion, a process thought to be catalyzed by alpha-expansins, and thus was a good system to identify expansins that were regulated by gravity. This study identified 7 new alpha-expansin cDNAs from cucumber seedlings (Cucumis sativus L. cv Burpee Hybrid II) and examined their expression patterns. Two alpha-expansins (CsExp3 and CsExp4) were more highly expressed in the peg and the root. Earlier reports stated that pegs tend not to form in the absence of gravity, so the expression levels were compared in the pegs of seedlings grown in space (STS-95), on a clinostat, and on earth (1 g). Pegs were observed to form at high frequency on clinostat and space-grown seedlings, yet on clinostats there was more than a 4-fold reduction in the expression of CsExp3 in the pegs of seedlings grown on clinostats vs. those grown at 1 g, while the CsExp4 gene appeared to be turned off (below detection limits). There were no detectable differences in expansin gene expression levels for the pegs of seedlings grown in space or in the orbiter environmental simulator (OES) (1 g) at NASA. The microgravity environment did not affect the expression of CsExp3 or CsExp4, and the clinostat did not simulate the microgravity environment well.

Nucleolar structure and proliferation activity of Arabidopsis root cells from seedlings germinated on the International Space Station

NASA Astrophysics Data System (ADS)

Matía, Isabel; González-Camacho, Fernando; Marco, Roberto; Kiss, John Z.; Gasset, Gilbert; Medina, Francisco-Javier

Seeds of Arabidopsis thaliana were sent to the International Space Station in the "Cervantes Mission" (Spanish Soyuz Mission). Seed germination was initiated in flight by supplying culture medium. Seedlings were grown for 4 days at 22 °C, and growth was stopped by the addition of paraformaldehyde fixative. Once back on the ground, samples were immediately processed for microscopy. A ground control experiment was simultaneously replicated. Glutaraldehyde-fixed root cells from seedlings grown in the Biorack on board of the Space Shuttle (STS-84 Mission) in similar conditions were also ultrastructurally examined. The length of seedlings grown at 1 g was conspicuously shorter than parallel samples grown under microgravity. We examined the morphology of the root meristematic cells, with a focus on their nucleoli in the cortex and stele. In general, root cortical cells proliferate at a higher rate and their nucleoli are more active than those of stele cells. While the stele showed longer cells with larger nucleoli in the flight samples, cortical cells from space-grown seedlings were shorter, more numerous and more densely packed than ground controls. However, nucleoli were smaller and less active in fast proliferating flight cells than in the ground controls. This reduced level of ribosome synthesis in the flight samples is probably the result of an accelerated cell cycle. An altered rate of cell proliferation may be detrimental for the plant and could be the reason for the reported smaller size of older space-grown seedlings. Finally, two-dimensional protein electrophoresis showed noticeable differences between space samples and ground controls.

The Application of Contrast Media for In Vivo Feature Enhancement in X-Ray Computed Tomography of Soil-Grown Plant Roots.

PubMed

Keyes, Samuel D; Gostling, Neil J; Cheung, Jessica H; Roose, Tiina; Sinclair, Ian; Marchant, Alan

2017-06-01

The use of in vivo X-ray microcomputed tomography (μCT) to study plant root systems has become routine, but is often hampered by poor contrast between roots, soil, soil water, and soil organic matter. In clinical radiology, imaging of poorly contrasting regions is frequently aided by the use of radio-opaque contrast media. In this study, we present evidence for the utility of iodinated contrast media (ICM) in the study of plant root systems using μCT. Different dilutions of an ionic and nonionic ICM (Gastrografin 370 and Niopam 300) were perfused into the aerial vasculature of juvenile pea plants via a leaf flap (Pisum sativum). The root systems were imaged via μCT, and a variety of image-processing approaches used to quantify and compare the magnitude of the contrast enhancement between different regions. Though the treatment did not appear to significantly aid extraction of full root system architectures from the surrounding soil, it did allow the xylem and phloem units of seminal roots and the vascular morphology within rhizobial nodules to be clearly visualized. The nonionic, low-osmolality contrast agent Niopam appeared to be well tolerated by the plant, whereas Gastrografin showed evidence of toxicity. In summary, the use of iodine-based contrast media allows usually poorly contrasting root structures to be visualized nondestructively using X-ray μCT. In particular, the vascular structures of roots and rhizobial nodules can be clearly visualized in situ.

Some Growth Aspects of Seymeria cassioicies

Treesearch

Charles M. Stangle; Lytton J. Musselman

1981-01-01

The root parasite, Seymeria cassioides, will not initiate height growth without attachment to a host root when grown under normal fertility conditions, although the seedling may remain alive for 40 days or more without a host. During this time the roots elongate markedly. Fresh pine root segments do not influence the direction of root growth. Although S....

VEG-01: Veggie Hardware Verification Testing

NASA Technical Reports Server (NTRS)

Massa, Gioia; Newsham, Gary; Hummerick, Mary; Morrow, Robert; Wheeler, Raymond

2013-01-01

The Veggie plant/vegetable production system is scheduled to fly on ISS at the end of2013. Since much of the technology associated with Veggie has not been previously tested in microgravity, a hardware validation flight was initiated. This test will allow data to be collected about Veggie hardware functionality on ISS, allow crew interactions to be vetted for future improvements, validate the ability of the hardware to grow and sustain plants, and collect data that will be helpful to future Veggie investigators as they develop their payloads. Additionally, food safety data on the lettuce plants grown will be collected to help support the development of a pathway for the crew to safely consume produce grown on orbit. Significant background research has been performed on the Veggie plant growth system, with early tests focusing on the development of the rooting pillow concept, and the selection of fertilizer, rooting medium and plant species. More recent testing has been conducted to integrate the pillow concept into the Veggie hardware and to ensure that adequate water is provided throughout the growth cycle. Seed sanitation protocols have been established for flight, and hardware sanitation between experiments has been studied. Methods for shipping and storage of rooting pillows and the development of crew procedures and crew training videos for plant activities on-orbit have been established. Science verification testing was conducted and lettuce plants were successfully grown in prototype Veggie hardware, microbial samples were taken, plant were harvested, frozen, stored and later analyzed for microbial growth, nutrients, and A TP levels. An additional verification test, prior to the final payload verification testing, is desired to demonstrate similar growth in the flight hardware and also to test a second set of pillows containing zinnia seeds. Issues with root mat water supply are being resolved, with final testing and flight scheduled for later in 2013.

Effect of channel size on sweet potato storage root enlargement in the Tuskegee University hydroponic nutrient film system

NASA Technical Reports Server (NTRS)

Morris, Carlton E.; Martinez, Edwin; Bonsi, C. K.; Mortley, Desmond G.; Hill, Walter A.; Ogbuehi, Cyriacus R.; Loretan, Phil A.

1989-01-01

The potential of the sweet potato as a food source for future long term manned space missions is being evaluated for NASA's Controlled Ecological Life Support Systems (CELSS) program. Sweet potatoes have been successfully grown in a specially designed Tuskegee University nutrient film technique (TU NFT) system. This hydroponic system yielded storage roots as high as 1790 g/plant fresh weight. In order to determine the effect of channel size on the yield of sweet potatoes, the width and depth of the growing channels were varied in two separate experiments. Widths were studied using the rectangular TU NFT channels with widths of 15 cm (6 in), 30 cm (12 in) and 45 cm (18 in). Channel depths of 5 cm (2 in), 10 cm (4 in), and 15 cm (6 in) were studied using a standard NASA fan shaped Biomass Production Chamber (BPC) channel. A comparison of preliminary results indicated that, except for storage root number, the growth and yield of sweet potatoes were not affected by channel width. Storage root yield was affected by channel depth although storage root number and foliage growth were not. Both experiments are being repeated.

Plant Growth Research for Food Production: Development and Testing of Expandable Tuber Growth Module

NASA Technical Reports Server (NTRS)

Cordova, Brennan A.

2017-01-01

Controlled and reliable growth of a variety of vegetable crops is an important capability for manned deep space exploration systems for providing nutritional supplementation and psychological benefits to crew members. Because current systems have been limited to leafy vegetables that require minimal root space, a major goal for these systems is to increase their ability to grow new types of crops, including tuber plants and root vegetables that require a large root space. An expandable root zone module and housing was developed to integrate this capability into the Vegetable Production System (Veggie). The expandable module uses a waterproof, gas-permeable bag with a structure that allows for root space to increase vertically throughout the growth cycle to accommodate for expanding tuber growth, while minimizing the required media mass. Daikon radishes were chosen as an ideal tuber crop for their subterraneous tuber size and rapid growth cycle, and investigations were done to study expanding superabsorbent hydrogels as a potential growth media. These studies showed improved water retention, but restricted oxygen availability to roots with pure gel media. It was determined that these hydrogels could be integrated in lower proportions into standard soil to achieve media expansion and water retention desired. Using the constructed module prototype and ideal gel and soil media mixture, daikon radishes are being grown in the system to test the capability and success of the system through a full growth cycle.

Plant Growth Research for Food Production: Development and Testing of Expandable Tuber Growth Module

NASA Technical Reports Server (NTRS)

Cordova, Brennan A.

2017-01-01

Controlled and reliable growth of a variety of vegetable crops is an important capability for manned deep space exploration systems for providing nutritional supplementation and psychological benefits to crew members. Because current systems have been limited to leafy vegetables that require minimal root space, a major goal for these systems is to increase their ability to grow new types of crops, including tuber plants and root vegetables that require a large root space. An expandable root zone module and housing was developed to integrate this capability into the Veggie growth system. The expandable module uses a waterproof, gas-permeable bag with a structure that allows for root space to increase vertically throughout the growth cycle to accommodate for expanding tuber growth, while minimizing the required media mass. Daikon radishes were chosen as an ideal tuber crop for their subterraneous tuber size and rapid growth cycle, and investigations were done to study expanding superabsorbent hydrogels as a potential growth media. These studies showed improved water retention, but restricted oxygen availability to roots with pure gel media. It was determined that these hydrogels could be integrated in lower proportions into standard soil to achieve media expansion and water retention desired. Using the constructed module prototype and ideal gel and soil media mixture, Daikon radishes were grown in the system to test the capability and success of the system through a full growth cycle.

Microgravity effects on water supply and substrate properties in porous matrix root support systems

NASA Technical Reports Server (NTRS)

Bingham, G. E.; Jones, S. B.; Or, D.; Podolski, I. G.; Levinskikh, M. A.; Sytchov, V. N.; Ivanova, T.; Kostov, P.; Sapunova, S.; Dandolov, I.;

Concentration of benzoxazinoids in roots of field-grown wheat (Triticum aestivum L.) varieties.

PubMed

Stochmal, Anna; Kus, Jan; Martyniuk, Stefan; Oleszek, Wieslaw

2006-02-22

Benzoxazinones are naturally occurring secondary metabolites of some Gramineae plants, responsible for their resistance to some pathogenic fungi and for their allelopathic action. Six varieties of winter wheat grown in fields under organic or conventional systems and 11 old accessions were tested for two consecutive seasons and three plant development stages for the concentration in their roots of cyclic hydroxamic acids and their degradation products. This is the first report of six benzoxazinones analyzed in plants grown in the field. An analytical technique employing LC-DAD was used for determination. It was shown that 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one, its degradation product 6-methoxybenzoxazolin-2-one, and the lactam 2-hydroxy-7-methoxy-1,4-benzoxazin-2-one were predominant compounds in all tested samples. Their concentrations significantly differed with plant development stage and season, but no significant differences were found between varieties and between plant cultivation systems. The concentrations of 2,4-dihydroxy-1,4-benzoxazin-3-one (DIBOA) and its degradation product benzoxazolin-2-one (BOA) were much lower, ranging from 60 to 430 mg/kg of dry matter, depending on accession, stage of development, and season. There was no significant difference found between plants grown in different cultivation systems, but there were significant differences between old and new varieties; concentrations of DIBOA and its derivatives were significantly lower in old accessions. It was concluded that the concentrations of DIBOA and BOA, which are precursors of highly fungicidal 2-aminophenol, 2-amino-3H-phenoxazin-3-one, and 2-acetylamino-3H-phenoxazin-3-one, are theoretically high enough to protect plants against some soilborne pathogens.

Systemic Infection of Maize, Sorghum, Rice, and Beet Seedlings with Fumonisin-Producing and Nonproducing Fusarium verticillioides Strains

PubMed Central

Dastjerdi, Raana; Karlovsky, Petr

2015-01-01

Two fumonisin-nonproducing strains of Fusarium verticillioides and their fumonisin producing progenitors were tested for aggressiveness toward maize, sorghum, rice, and beetroot seedlings grown under greenhouse conditions. None of the plants showed obvious disease symptoms after root dip inoculation. Fungal biomass was determined by species-specific real-time PCR. No significant (P = 0.05) differences in systemic colonization were detected between the wild type strains and mutants not producing fumonisins. F. verticillioides was not detected in any of the non-inoculated control plants. The fungus grew from roots to the first two internodes/leaves of maize, rice and beet regardless of fumonisin production. The systemic growth of F. verticillioides in sorghum was limited. The results showed that fumonisin production was not required for the infection of roots of maize, rice and beet by F. verticillioides. PMID:26672472

CASIROZ: Root parameters and types of ectomycorrhiza of young beech plants exposed to different ozone and light regimes.

PubMed

Zeleznik, P; Hrenko, M; Then, C; Koch, N; Grebenc, T; Levanic, T; Kraigher, H

2007-03-01

Tropospheric ozone (O(3)) triggers physiological changes in leaves that affect carbon source strength leading to decreased carbon allocation below-ground, thus affecting roots and root symbionts. The effects of O(3) depend on the maturity-related physiological state of the plant, therefore adult and young forest trees might react differently. To test the applicability of young beech plants for studying the effects of O(3) on forest trees and forest stands, beech seedlings were planted in containers and exposed for two years in the Kranzberg forest FACOS experiment (Free-Air Canopy O(3) Exposure System, http://www.casiroz.de ) to enhanced ozone concentration regime (ambient [control] and double ambient concentration, not exceeding 150 ppb) under different light conditions (sun and shade). After two growing seasons the biomass of the above- and below-ground parts, beech roots (using WinRhizo programme), anatomical and molecular (ITS-RFLP and sequencing) identification of ectomycorrhizal types and nutrient concentrations were assessed. The mycorrhization of beech seedlings was very low ( CA. 5 % in shade, 10 % in sun-grown plants), no trends were observed in mycorrhization (%) due to ozone treatment. The number of Cenococcum geophilum type of ectomycorrhiza, as an indicator of stress in the forest stands, was not significantly different under different ozone treatments. It was predominantly occurring in sun-exposed plants, while its majority share was replaced by Genea hispidula in shade-grown plants. Different light regimes significantly influenced all parameters except shoot/root ratio and number of ectomycorrhizal types. In the ozone fumigated plants the number of types, number of root tips per length of 1 to 2 mm root diameter, root length density per volume of soil and concentration of Mg were significantly lower than in control plants. Trends to a decrease were found in root, shoot, leaf, and total dry weights, total number of root tips, number of vital mycorrhizal root tips, fine root (mass) density, root tip density per surface, root area index, concentration of Zn, and Ca/Al ratio. Due to the general reduction in root growth indices and nutrient cycling in ozone-fumigated plants, alterations in soil carbon pools could be predicted.

Evaluation of hyperaccumulator plant species grown in metalliferous sites in Albania

NASA Astrophysics Data System (ADS)

Babani, F.; Civici, N.; Mullaj, A.; Kongjika, E.; Ylli, A.

2007-04-01

Heavy metal contamination of soils causes serious problems to our society. A small number of interesting plant species have been identified that can grow in soils containing high levels of heavy metals, and can also accumulate these metals to high concentrations in the shoot. The heavy metal contents in root, shoot, leaves and flowers of spontaneous plants grown in metalliferous sites in Albania together with the elemental composition of the native soils were determined by X-ray fluorescence spectrometry. Efficiency of photosynthetic apparatus of analyzed ecotypes was evaluated via chlorophyll fluorescence imaging during induction kinetics. Response of plant root system to the presence of metals, the available pools of metals to plants, effect of plant biomass to phytoextraction, photosynthetic pigment metabolism and chlorophyll fluorescence signature of leaves allowed to characterize hyperaccumulator properties and to detect the variation between selected ecotypes to heavy metal accumulation.

Douglas fir (pseudotsuga menziesii) plantlets responses to as, PB, and sb-contaminated soils from former mines.

PubMed

Bonet, Amandine; Pascaud, Grégoire; Faugeron, Céline; Soubrand, Marilyne; Joussein, Emmanuel; Gloaguen, Vincent; Saladin, Gaëlle

2016-01-01

Phytoremediation of metalloids by conifers is not widely studied although they may be relevant for several contaminated sites, especially those located in cold areas and sometimes under dry climates. Here, seeds of Douglas fir were sown in greenhouse on three soils collected in two French former mines: a gold mine (soils L1 and L2) and a lead and silver mine (soil P). These soils are highly contaminated by Pb, As, and Sb at different concentrations. Plants were harvested after ten weeks. Growth parameters, primary metabolite content, and shoot and root ionomes were determined. Douglas firs grown on the soils L1 and P had a lower biomass than controls and a higher oxidation status whereas those grown on the soil L2 exhibited a more developed root system and only slight modifications of carbon and nitrogen nutrition. Based on trace element (TE) concentrations in shoots and roots and their translocation factor (TF), Douglas fir could be a relevant candidate for As phytoextraction (0.8 g. kg(-1) dry weight in shoots and a TF of 1.1) and may be used to phytostabilize Pb and Sb (8.8 g and 127 mg. kg(-1) in roots for Pb and Sb, respectively, and TF lower than 0.1).

Rapid Phenotyping of Root Systems of Brachypodium Plants Using X-ray Computed Tomography: a Comparative Study of Soil Types and Segmentation Tools

NASA Astrophysics Data System (ADS)

Varga, T.; McKinney, A. L.; Bingham, E.; Handakumbura, P. P.; Jansson, C.

2017-12-01

Plant roots play a critical role in plant-soil-microbe interactions that occur in the rhizosphere, as well as in processes with important implications to farming and thus human food supply. X-ray computed tomography (XCT) has been proven to be an effective tool for non-invasive root imaging and analysis. Selected Brachypodium distachyon phenotypes were grown in both natural and artificial soil mixes. The specimens were imaged by XCT, and the root architectures were extracted from the data using three different software-based methods; RooTrak, ImageJ-based WEKA segmentation, and the segmentation feature in VG Studio MAX. The 3D root image was successfully segmented at 30 µm resolution by all three methods. In this presentation, ease of segmentation and the accuracy of the extracted quantitative information (root volume and surface area) will be compared between soil types and segmentation methods. The best route to easy and accurate segmentation and root analysis will be highlighted.

Foxtail Millet [Setaria italica (L.) Beauv.] Grown under Low Nitrogen Shows a Smaller Root System, Enhanced Biomass Accumulation, and Nitrate Transporter Expression.

PubMed

Nadeem, Faisal; Ahmad, Zeeshan; Wang, Ruifeng; Han, Jienan; Shen, Qi; Chang, Feiran; Diao, Xianmin; Zhang, Fusuo; Li, Xuexian

2018-01-01

Foxtail millet (FM) [ Setaria italica (L.) Beauv.] is a grain and forage crop well adapted to nutrient-poor soils. To date little is known how FM adapts to low nitrogen (LN) at the morphological, physiological, and molecular levels. Using the FM variety Yugu1, we found that LN led to lower chlorophyll contents and N concentrations, and higher root/shoot and C/N ratios and N utilization efficiencies under hydroponic culture. Importantly, enhanced biomass accumulation in the root under LN was in contrast to a smaller root system, as indicated by significant decreases in total root length; crown root number and length; and lateral root number, length, and density. Enhanced carbon allocation toward the root was rather for significant increases in average diameter of the LN root, potentially favorable for wider xylem vessels or other anatomical alterations facilitating nutrient transport. Lower levels of IAA and CKs were consistent with a smaller root system and higher levels of GA may promote root thickening under LN. Further, up-regulation of SiNRT1.1, SiNRT2.1, and SiNAR2.1 expression and nitrate influx in the root and that of SiNRT1.11 and SiNRT1.12 expression in the shoot probably favored nitrate uptake and remobilization as a whole. Lastly, more soluble proteins accumulated in the N-deficient root likely as a result of increases of N utilization efficiencies. Such "excessive" protein-N was possibly available for shoot delivery. Thus, FM may preferentially transport carbon toward the root facilitating root thickening/nutrient transport and allocate N toward the shoot maximizing photosynthesis/carbon fixation as a primary adaptive strategy to N limitation.

Tantalum films with well-controlled roughness grown by oblique incidence deposition

NASA Astrophysics Data System (ADS)

Rechendorff, K.; Hovgaard, M. B.; Chevallier, J.; Foss, M.; Besenbacher, F.

2005-08-01

We have investigated how tantalum films with well-controlled surface roughness can be grown by e-gun evaporation with oblique angle of incidence between the evaporation flux and the surface normal. Due to a more pronounced shadowing effect the root-mean-square roughness increases from about 2 to 33 nm as grazing incidence is approached. The exponent, characterizing the scaling of the root-mean-square roughness with length scale (α), varies from 0.75 to 0.93, and a clear correlation is found between the angle of incidence and root-mean-square roughness.

The multi-year effects of repeatedly growing cotton with moderate resistance to Meloidogyne incognita

PubMed Central

Kemerait, Robert C.

2009-01-01

Meloidogyne incognita causes more damage to cotton in the US than any other pathogen. The objective of this study was to document the cumulative effect of moderate resistance on M. incognita population density, root galling, and yield suppression in the southern United States on a moderately resistant cotton genotype grown continuously for three years. Cotton genotypes were Phytogen PH98-3196 (77% suppression of M. incognita), Acala NemX (85% suppression of M. incognita), and Delta and Pine Land DP458 B/R (susceptible standard, 0% suppression). Cotton was grown in fumigated and non-fumigated plots to measure yield loss. Each genotype and nematicide combination was planted in the same place for three years at two sites to document cumulative effects. In 2006, following three years of the different genotypes, all plots at one site were planted with susceptible cotton to document residual effects of planting resistant genotypes. Root galling and nematode population densities in the soil were significantly lower, and percentage yield suppression was numerically lower, when moderately resistant cotton was grown compared to the susceptible standard in both fields in all three years. Differences between susceptible and moderately resistant genotypes are established quickly (after only one season) and then either maintained at similar levels or slightly increased in subsequent years depending on initial nematode levels. However, when susceptible cotton was grown following three years of the moderately resistant genotypes, the nematode suppression provided by moderate resistance was undetectable by the end of the first season. Moderately resistant cotton genotypes are more beneficial than previously reported and should be pursued for nematode management. Rotation of moderately resistant and susceptible cotton could be used along with nematicides to manage root-knot nematodes in a continuous cotton cropping system and reduce selection pressure on the nematodes. PMID:22661787

Effects of benzoic and cinnamic acids on growth, mineral composition, and chlorophyll content of soybean.

PubMed

Baziramakenga, R; Simard, R R; Leroux, G D

1994-11-01

Organic acids are major water-soluble allelochemicals found in soil infested with quackgrass and are involved in several processes that are important in plant growth and development. This study was carried out to gain more information on the effects of benzoic acid (BEN) andtrans-cinnamic acid (CIN) on growth, mineral composition, and chlorophyll content of soybean [Glycine max (L.) Merr. cv. Maple Bell] grown in nutrient solution. The two allelochemicals reduced root and shoot dry biomass of soybean. Treated plants had fewer lateral roots and tended to grow more horizontally compared to the untreated plants. Lateral roots were stunted and less flexible. The amounts of P, K, Mg, Mn, Cl(-), and SO 4 (2-) were lower, and Zn and Fe contents were higher in roots of plants grown with BEN or CIN as compared to untreated plants. Shoots of plants grown with the allelochemical showed greater accumulation of Ca, Mg, and Zn, whereas P and Fe contents were reduced. The BEN and CIN also caused reductions in leaf chlorophyll content. The BEN and CIN may be responsible for negative allelopathic effects of quackgrass on soybean by inhibiting root growth, by altering ion uptake and transport, and by reducing chlorophyll content.

Accumulation of heavy metals by vegetables grown in mine wastes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cobb, G.P.; Sands, K.; Waters, M.

2000-03-01

Lead, cadmium, arsenic, and zinc were quantified in mine wastes and in soils mixed with mine wastes. Metal concentrations were found to be heterogeneous in the wastes. Iceberg lettuce, Cherry Belle radishes, Roma bush beans, and Better Boy tomatoes were cultivated in mine wastes and in waste-amended soils. Lettuce and radishes had 100% survival in the 100% mine waste treatments compared to 0% and 25% survival for tomatoes and beans, respectively. Metal concentrations were determined in plant tissues to determine uptake and distribution of metals in the edible plant parts. Individual soil samples were collected beneath each plant to assessmore » metal content in the immediate plant environment. This analysis verified heterogeneous metal content of the mine wastes. The four plant species effectively accumulated and translocated lead, cadmium, arsenic, and zinc. Tomato and bean plants contained the four metals mainly in the roots and little was translocated to the fruits. Radish roots accumulated less metals compared to the leaves, whereas lettuce roots and leaves accumulated similar concentrations of the four metals. Lettuce leaves and radish roots accumulated significantly more metals than bean and tomato fruits. This accumulation pattern suggests that consumption of lettuce leaves or radish roots from plants grown in mine wastes would pose greater risks to humans and wildlife than would consumption of beans or tomatoes grown in the same area. The potential risk may be mitigated somewhat in humans, as vegetables grown in mine wastes exhibited stunted growth and chlorosis.« less

Silicon alleviates Cd stress of wheat seedlings (Triticum turgidum L. cv. Claudio) grown in hydroponics.

PubMed

Rizwan, M; Meunier, J-D; Davidian, J-C; Pokrovsky, O S; Bovet, N; Keller, C

2016-01-01

We investigated the potential role of silicon in improving tolerance and decreasing cadmium (Cd) toxicity in durum wheat (Triticum turgidum L. durum) either through a reduced Cd uptake or exclusion/sequestration in non-metabolic tissues. For this, plants were grown in hydroponic conditions for 10 days either in presence or absence of 1 mM Si and for 11 additional days in various Cd concentrations (0, 0.5, 5.0 and 50 μM). After harvesting, morphological and physiological parameters as well as elemental concentrations were recorded. Cadmium caused reduction in growth parameters, photosynthetic pigments and mineral nutrient concentrations both in shoots and roots. Shoot and root contents of malate, citrate and aconitate increased, while contents of phosphate, nitrate and sulphate decreased with increasing Cd concentrations in plants. Addition of Si to the nutrient solution mitigated these adverse effects: Cd concentration in shoots decreased while concentration of Cd adsorbed at the root cell apoplasmic level increased together with Zn uptake by roots. Overall, total Cd uptake decreased in presence of Si. There was no co-localisation of Cd and Si either at the shoot or at the root levels. No Cd was detected in leaf phytoliths. In roots, Cd was mainly detected in the cortical parenchyma and Si at the endodermis level, while analysis of the outer thin root surface of the plants grown in the 50 μM Cd + 1 mM Si treatment highlighted non-homogeneous Cd and Si enrichments. These data strongly suggest the existence of a root localised protection mechanism consisting in armoring the root surface by Si- and Cd-bearing compounds and in limiting root-shoot translocation.

An Efficient Method for Adventitious Root Induction from Stem Segments of Brassica Species

PubMed Central

Srikanth, Sandhya; Choong, Tsui Wei; Yan, An; He, Jie; Chen, Zhong

2016-01-01

Plant propagation via in vitro culture is a very laborious and time-consuming process. The growth cycle of some of the crop species is slow even in the field and the consistent commercial production is hard to maintain. Enhanced methods of reduced cost, materials and labor significantly impact the research and commercial production of field crops. In our studies, stem-segment explants of Brassica species were found to generate adventitious roots (AR) in aeroponic systems in less than a week. As such, the efficiency of rooting from stem explants of six cultivar varieties of Brassica spp was tested without using any plant hormones. New roots and shoots were developed from Brassica alboglabra (Kai Lan), B. oleracea var. acephala (purple kale), B. rapa L. ssp. chinensis L (Pai Tsai, Nai Bai C, and Nai Bai T) explants after 3 to 5 days of growing under 20 ± 2°C cool root zone temperature (C-RZT) and 4 to 7 days in 30 ± 2°C ambient root zone temperature (A-RZT). At the base of cut end, anticlinal and periclinal divisions of the cambial cells resulted in secondary xylem toward pith and secondary phloem toward cortex. The continuing mitotic activity of phloem parenchyma cells led to a ring of conspicuous white callus. Root initials formed from the callus which in turn developed into ARs. However, B. rapa var. nipposinica (Mizuna) explants were only able to root in C-RZT. All rooted explants were able to develop into whole plants, with higher biomass obtained from plants that grown in C-RZT. Moreover, explants from both RZTs produced higher biomass than plants grown from seeds (control plants). Rooting efficiency was affected by RZTs and explant cuttings of donor plants. Photosynthetic CO2 assimilation rate (Asat) and stomatal conductance (gssat) were significantly differentiated between plants derived from seeds and explants at both RZTs. All plants in A-RZT had highest transpiration rates. PMID:27446170

Survival and Transfer of Murine Norovirus within a Hydroponic System during Kale and Mustard Microgreen Harvesting.

PubMed

Wang, Qing; Kniel, Kalmia E

2016-01-15

Hydroponically grown microgreens are gaining in popularity, but there is a lack of information pertaining to their microbiological safety. The potential risks associated with virus contamination of crops within a hydroponic system have not been studied to date. Here a human norovirus (huNoV) surrogate (murine norovirus [MNV]) was evaluated for its ability to become internalized from roots to edible tissues of microgreens. Subsequently, virus survival in recirculated water without adequate disinfection was assessed. Kale and mustard seeds were grown on hydroponic pads (for 7 days with harvest at days 8 to 12), edible tissues (10 g) were cut 1 cm above the pads, and corresponding pieces (4 cm by 4 cm) of pads containing only roots were collected separately. Samples were collected from a newly contaminated system (recirculated water inoculated with ∼3 log PFU/ml MNV on day 8) and from a previously contaminated system. (A contaminated system without adequate disinfection or further inoculation was used for production of another set of microgreens.) Viral titers and RNA copies were quantified by plaque assay and real-time reverse transcription (RT)-PCR. The behaviors of MNV in kale and mustard microgreens were similar (P > 0.05). MNV was detected in edible tissues and roots after 2 h postinoculation, and the levels were generally stable during the first 12 h. Relatively low levels (∼2.5 to ∼1.5 log PFU/sample of both edible tissues and roots) of infectious viruses were found with a decreasing trend over time from harvest days 8 to 12. However, the levels of viral RNA present were higher and consistently stable (∼4.0 to ∼5.5 log copies/sample). Recirculated water maintained relatively high levels of infectious MNV over the period of harvest, from 3.54 to 2.73 log PFU/ml. Importantly, cross-contamination occurred easily; MNV remained infectious in previously contaminated hydroponic systems for up to 12 days (2.26 to 1.00 PFU/ml), and MNV was detected in both edible tissues and roots. Here we see that viruses can be recirculated in water, even after an initial contamination event is removed, taken up through the roots of microgreens, and transferred to edible tissues. The ease of product contamination shown here reinforces the need for proper sanitation. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

Survival and Transfer of Murine Norovirus within a Hydroponic System during Kale and Mustard Microgreen Harvesting

PubMed Central

Wang, Qing

2015-01-01

Hydroponically grown microgreens are gaining in popularity, but there is a lack of information pertaining to their microbiological safety. The potential risks associated with virus contamination of crops within a hydroponic system have not been studied to date. Here a human norovirus (huNoV) surrogate (murine norovirus [MNV]) was evaluated for its ability to become internalized from roots to edible tissues of microgreens. Subsequently, virus survival in recirculated water without adequate disinfection was assessed. Kale and mustard seeds were grown on hydroponic pads (for 7 days with harvest at days 8 to 12), edible tissues (10 g) were cut 1 cm above the pads, and corresponding pieces (4 cm by 4 cm) of pads containing only roots were collected separately. Samples were collected from a newly contaminated system (recirculated water inoculated with ∼3 log PFU/ml MNV on day 8) and from a previously contaminated system. (A contaminated system without adequate disinfection or further inoculation was used for production of another set of microgreens.) Viral titers and RNA copies were quantified by plaque assay and real-time reverse transcription (RT)-PCR. The behaviors of MNV in kale and mustard microgreens were similar (P > 0.05). MNV was detected in edible tissues and roots after 2 h postinoculation, and the levels were generally stable during the first 12 h. Relatively low levels (∼2.5 to ∼1.5 log PFU/sample of both edible tissues and roots) of infectious viruses were found with a decreasing trend over time from harvest days 8 to 12. However, the levels of viral RNA present were higher and consistently stable (∼4.0 to ∼5.5 log copies/sample). Recirculated water maintained relatively high levels of infectious MNV over the period of harvest, from 3.54 to 2.73 log PFU/ml. Importantly, cross-contamination occurred easily; MNV remained infectious in previously contaminated hydroponic systems for up to 12 days (2.26 to 1.00 PFU/ml), and MNV was detected in both edible tissues and roots. Here we see that viruses can be recirculated in water, even after an initial contamination event is removed, taken up through the roots of microgreens, and transferred to edible tissues. The ease of product contamination shown here reinforces the need for proper sanitation. PMID:26567309

Interactions of light and gravity on growth, orientation, and lignin biosynthesis in mung beans

NASA Technical Reports Server (NTRS)

Jahns, G. C.

1984-01-01

Mung beans (Vigna radiata L.) seedlings grown on the third Space Transport Mission (STS-3) showed marked orientation problems (some of the stems elongated horizontally and many of the roots were growing upward) and had a lower lignin content than the ground based controls. This research was initiated to determine if the atypical growth characteristics of mung beans grown in microgravity could be simulated using horizontal clinostats. Most of the effort focused on the design, construction and testing of the clinostats. In order to closely approximate the growth conditions of the plants grown in the plant growth unit on STS-3, cylindrical lexan minichambers were constructed. Results showed that plants grown using these clinostats in the horizontal position exhibit similar growth characteristics to the plants grown on STS-3 (disorientation of both stems and roots), while the vertical stationary and vertical rotating controls exhibit normal growth.

Differential effects of fine root morphology on water dynamics in the root-soil interface

NASA Astrophysics Data System (ADS)

DeCarlo, K. F.; Bilheux, H.; Warren, J.

2017-12-01

Soil water uptake form plants, particularly in the rhizosphere, is a poorly understood question in the plant and soil sciences. Our study analyzed the role of belowground plant morphology on soil structural and water dynamics of 5 different plant species (juniper, grape, maize, poplar, maple), grown in sandy soils. Of these, the poplar system was extended to capture drying dynamics. Neutron radiography was used to characterize in-situ dynamics of the soil-water-plant system. A joint map of root morphology and soil moisture was created for the plant systems using digital image processing, where soil pixels were connected to associated root structures via minimum distance transforms. Results show interspecies emergent behavior - a sigmoidal relationship was observed between root diameter and bulk/rhizosphere soil water content difference. Extending this as a proxy for extent of rhizosphere development with root age, we observed a logistic growth pattern for the rhizosphere: minimal development in the early stages is superceded by rapid onset of rhizosphere formation, which then stabilizes/decays with the likely root suberization. Dynamics analysis of water content differences between the root/rhizosphere, and rhizosphere/bulk soil interface highlight the persistently higher water content in the root at all water content and root size ranges. At the rhizosphere/bulk soil interface, we observe a shift in soil water dynamics by root size: in super fine roots, we observe that water content is primarily lower in the rhizosphere under wetter conditions, which then gradually increases to a relatively higher water content under drier conditions. This shifts to a persistently higher rhizosphere water content relative to bulk soil in both wet/dry conditions with increased root size, suggesting that, by size, the finest root structures may contribute the most to total soil water uptake in plants.

Hydraulics and gas exchange recover more rapidly from severe drought stress in small pot-grown grapevines than in field-grown plants.

PubMed

Romero, Pascual; Botía, Pablo; Keller, Markus

2017-09-01

Modifications of plant hydraulics and shoot resistances (R shoot ) induced by water withholding followed by rewatering, and their relationships with plant water status, leaf gas exchange and water use efficiency at the leaf level, were investigated in pot-grown and field-grown, own-rooted Syrah grapevines in an arid climate. Water stress induced anisohydric behavior, gradually reducing stomatal conductance (g s ) and leaf photosynthesis (A) in response to decreasing midday stem water potential (Ψ s ). Water stress also rapidly increased intrinsic water-use efficiency (A/g s ); this effect persisted for many days after rewatering. Whole-plant (K plant ), canopy (K canopy ), shoot (K shoot ) and leaf (K leaf ) hydraulic conductances decreased during water stress, in tune with the gradual decrease in Ψ s , leaf gas exchange and whole plant water use. Water-stressed vines also had a lower Ψ gradient between stem and leaf (ΔΨ l ), which was correlated with lower leaf transpiration rate (E). E and ΔΨ l increased with increasing vapour pressure deficit (VPD) in non-stressed control vines but not in stressed vines. Perfusion of xylem-mobile dye showed that water flow to petioles and leaves was substantially reduced or even stopped under moderate and severe drought stress. Leaf blade hydraulic resistance accounted for most of the total shoot resistance. However, hydraulic conductance of the whole root system (K root ) was not significantly reduced until water stress became very severe in pot-grown vines. Significant correlations between K plant , K canopy and Ψ s , K canopy and leaf gas exchange, K leaf and Ψ s , and K leaf and A support a link between water supply, leaf water status and gas exchange. Upon re-watering, Ψ s recovered faster than gas exchange and leaf-shoot hydraulics. A gradual recovery of hydraulic functionality of plant organs was also observed, the leaves being the last to recover after rewatering. In pot-grown vines, K canopy recovered rather quickly following restoration of Ψ s , although gas exchange recovery did not directly depend on recovery of K canopy . In field-grown vines, recovery of water status, gas exchange and hydraulic functionality was slower than in pot-grown plants, and low g s after rewatering was related to sustained decreased K plant , K canopy and K shoot and lower water transport to leaves. These results suggest that caution should be exercised when scaling up conclusions from experiments with small pot-grown plants to field conditions. Copyright © 2017 Elsevier GmbH. All rights reserved.

A Proteinaceous Elicitor Sm1 from the Beneficial Fungus Trichoderma virens Is Required for Induced Systemic Resistance in Maize1[W

PubMed Central

Djonović, Slavica; Vargas, Walter A.; Kolomiets, Michael V.; Horndeski, Michelle; Wiest, Aric; Kenerley, Charles M.

2007-01-01

We have previously shown that the beneficial filamentous fungus Trichoderma virens secretes the highly effective hydrophobin-like elicitor Sm1 that induces systemic disease resistance in the dicot cotton (Gossypium hirsutum). In this study we tested whether colonization of roots by T. virens can induce systemic protection against a foliar pathogen in the monocot maize (Zea mays), and we further demonstrated the importance of Sm1 during maize-fungal interactions using a functional genomics approach. Maize seedlings were inoculated with T. virens Gv29-8 wild type and transformants in which SM1 was disrupted or constitutively overexpressed in a hydroponic system or in soil-grown maize seedlings challenged with the pathogen Colletotrichum graminicola. We show that similar to dicot plants, colonization of maize roots by T. virens induces systemic protection of the leaves inoculated with C. graminicola. This protection was associated with notable induction of jasmonic acid- and green leaf volatile-biosynthetic genes. Neither deletion nor overexpression of SM1 affected normal growth or development of T. virens, conidial germination, production of gliotoxin, hyphal coiling, hydrophobicity, or the ability to colonize maize roots. Plant bioassays showed that maize grown with SM1-deletion strains exhibited the same levels of systemic protection as non-Trichoderma-treated plants. Moreover, deletion and overexpression of SM1 resulted in significantly reduced and enhanced levels of disease protection, respectively, compared to the wild type. These data together indicate that T. virens is able to effectively activate systemic disease protection in maize and that the functional Sm1 elicitor is required for this activity. PMID:17885089

Global expression pattern comparison between low phosphorus insensitive 4 and WT Arabidopsis reveals an important role of reactive oxygen species and jasmonic acid in the root tip response to phosphate starvation

PubMed Central

Chacón-López, Alejandra; Ibarra-Laclette, Enrique; Sánchez-Calderón, Lenin; Gutiérrez-Alanís, Dolores

2011-01-01

Plants are exposed to several biotic and abiotic stresses. A common environmental stress that plants have to face both in natural and agricultural ecosystems that impacts both its growth and development is low phosphate (Pi) availability. There has been an important progress in the knowledge of the molecular mechanisms by which plants cope with Pi deficiency. However, the mechanisms that mediate alterations in the architecture of the Arabidopsis root system responses to Pi starvation are still largely unknown. One of the most conspicuous developmental effects of low Pi on the Arabidopsis root system is the inhibition of primary root growth that is accompanied by loss of root meristematic activity. To identify signalling pathways potentially involved in the Arabidpsis root meristem response to Pi-deprivation, here we report the global gene expression analysis of the root tip of wild type and low phosphorus insensitive4 (lpi4) mutant grown under Pi limiting conditions. Differential gene expression analysis and physiological experiments show that changes in the redox status, probably mediated by jasmonic acid and ethylene, play an important role in the primary root meristem exhaustion process triggered by Pi-starvation. PMID:21368582

Role of HSP101 in the stimulation of nodal root development from the coleoptilar node by light and temperature in maize (Zea mays L.) seedlings.

PubMed

López-Frías, Guillermo; Martínez, Luz María; Ponce, Georgina; Cassab, Gladys I; Nieto-Sotelo, Jorge

2011-08-01

Nodal roots (NRs) constitute the prevalent root system of adult maize plants. NRs emerge from stem nodes located below or above ground, and little is known about their inducing factors. Here, it is shown that precocious development of NRs at the coleoptilar node (NRCNs) occurred in maize seedlings when: (i) dark grown and stimulated by the concurrent action of a single light shock of low intensity white light (2 μmol m(-2) s(-1)) and a single heat shock; (ii) grown under a photoperiod of low intensity light (0.1 μmol m(-2) s(-1)); or (iii) grown in the dark under a thermoperiod (28 °C/34 °C). The light shock effects were synergistic with heat shock and with the photoperiod, whereas the thermoperiodical and photoperiodical effects were additive. Dissection of the primary root or the root cap, to mimic the fatal consequences of severe heat shock, caused negligible effects on NRCN formation, indicating that the shoot is directly involved in perception of the heat shock-inducible signal that triggered NRCN formation. A comparison between hsp101-m5::Mu1/hsp101-m5::Mu1 and Hsp101/Hsp101 seedlings indicated that the heat shock protein 101 (HSP101) chaperone inhibited NRCN formation in the light and in the dark. Stimulation of precocious NRCN formation by light and heat shocks was affected by genetic background and by the stage of seedling development. HSP101 protein levels increased in the coleoptilar node of induced wild-type plants, particularly in the procambial region, where NRCN formation originated. The adaptive relevance of development of NRCNs in response to these environmental cues and hypothetical mechanisms of regulation by HSP101 are discussed. © 2011 The Author(s).

Root-Crown Relations of Young Sugar Maple and Yellow Birch

Treesearch

Carl H. Tubbs

1977-01-01

Young forest-grown sugar maple and yellow birch (1 to 6 inches d.b.h.) crowns were mapped and roots excavated. Crown dimensions were compared. Sugar maple roots usually terminated within a few feet of the crown perimeter. Yellow birch roots frequently terminated well outside crown perimeters and roots of birch were more irregularly distributed than those of maple....

Developing suitable methods for effective characterization of electrical properties of root segments

NASA Astrophysics Data System (ADS)

Ehosioke, Solomon; Phalempin, Maxime; Garré, Sarah; Kemna, Andreas; Huisman, Sander; Javaux, Mathieu; Nguyen, Frédéric

2017-04-01

The root system represents the hidden half of the plant which plays a key role in food production and therefore needs to be well understood. Root system characterization has been a great challenge because the roots are buried in the soil. This coupled with the subsurface heterogeneity and the transient nature of the biogeochemical processes that occur in the root zone makes it difficult to access and monitor the root system over time. The traditional method of point sampling (root excavation, monoliths, minirhizotron etc.) for root investigation does not account for the transient nature and spatial variability of the root zone, and it often disturbs the natural system under investigation. The quest to overcome these challenges has led to an increase in the application of geophysical methods. Recent studies have shown a correlation between bulk electrical resistivity and root mass density, but an understanding of the contribution of the individual segments of the root system to that bulk signal is still missing. This study is an attempt to understand the electrical properties of roots at the segment scale (1-5cm) for more effective characterization of electrical signal of the full root architecture. The target plants were grown in three different media (pot soil, hydroponics and a mixture of sand, perlite and vermiculite). Resistance measurements were carried out on a single segment of each study plant using a voltmeter while the diameter was measured using a digital calliper. The axial resistance was calculated using the measured resistance and the geometric parameters. This procedure was repeated for each plant replica over a period of 75 days which enabled us to study the effects of age, growth media, diameter and length on the electrical response of the root segments of the selected plants. The growth medium was found to have a significant effect on the root electrical response, while the effect of root diameter on their electrical response was found to vary among the plants. More work is still required to further validate these results and also to develop better systems to study the electrical behaviour of root segments. Findings from our review entitled "an overview of the geophysical approach to root investigation", suggest that SIP and EIT geophysical methods could be very useful for root investigations, thus more work is in progress to develop these systems for assessing the root electrical response at various scales.

Prioritizing quantitative trait loci for root system architecture in tetraploid wheat.

PubMed

Maccaferri, Marco; El-Feki, Walid; Nazemi, Ghasemali; Salvi, Silvio; Canè, Maria Angela; Colalongo, Maria Chiara; Stefanelli, Sandra; Tuberosa, Roberto

2016-02-01

Optimization of root system architecture (RSA) traits is an important objective for modern wheat breeding. Linkage and association mapping for RSA in two recombinant inbred line populations and one association mapping panel of 183 elite durum wheat (Triticum turgidum L. var. durum Desf.) accessions evaluated as seedlings grown on filter paper/polycarbonate screening plates revealed 20 clusters of quantitative trait loci (QTLs) for root length and number, as well as 30 QTLs for root growth angle (RGA). Divergent RGA phenotypes observed by seminal root screening were validated by root phenotyping of field-grown adult plants. QTLs were mapped on a high-density tetraploid consensus map based on transcript-associated Illumina 90K single nucleotide polymorphisms (SNPs) developed for bread and durum wheat, thus allowing for an accurate cross-referencing of RSA QTLs between durum and bread wheat. Among the main QTL clusters for root length and number highlighted in this study, 15 overlapped with QTLs for multiple RSA traits reported in bread wheat, while out of 30 QTLs for RGA, only six showed co-location with previously reported QTLs in wheat. Based on their relative additive effects/significance, allelic distribution in the association mapping panel, and co-location with QTLs for grain weight and grain yield, the RSA QTLs have been prioritized in terms of breeding value. Three major QTL clusters for root length and number (RSA_QTL_cluster_5#, RSA_QTL_cluster_6#, and RSA_QTL_cluster_12#) and nine RGA QTL clusters (QRGA.ubo-2A.1, QRGA.ubo-2A.3, QRGA.ubo-2B.2/2B.3, QRGA.ubo-4B.4, QRGA.ubo-6A.1, QRGA.ubo-6A.2, QRGA.ubo-7A.1, QRGA.ubo-7A.2, and QRGA.ubo-7B) appear particularly valuable for further characterization towards a possible implementation of breeding applications in marker-assisted selection and/or cloning of the causal genes underlying the QTLs. © The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Assessment of edibility and effect of arbuscular mycorrhizal fungi on Solanum melongena L. grown under heavy metal(loid) contaminated soil.

PubMed

Chaturvedi, Ritu; Favas, Paulo; Pratas, João; Varun, Mayank; Paul, Manoj S

2018-02-01

Arbuscular mycorrhizal fungi (AMF) aids in plant establishment at heavy metal(loid) (HM) contaminated soils, strengthening plant defense system along with promoting growth. A pot experiment was carried out to evaluate the effect of AMF on eggplants grown under HM stress. Further, the potential health risks of HM exposure to the humans via dietary intake of eggplant were also estimated. Results showed that AMF application improved growth, biomass and antioxidative defense response of plants against HM stress. Significant difference (p ≤ 0.001) in parameters under study was found on increasing metal dose and on application of AMF. Among metal(loid)s maximum uptake was recorded for Pb (29.64mgkg - 1 in roots; 23.08mgkg - 1 in shoot) followed by As (3.84mgkg - 1 in roots; 8.20mgkg - 1 in shoot) and, Cd (0.96mgkg - 1 in roots; 2.12mgkg - 1 in shoot). Based on the accumulation of HM in edible part, Hazard Quotient (HQ) was calculated. HQ was found to be > 1 for Pb, which highlights the risks associated with consumption of Eggplants grown on Pb contaminated soil. However this potential, which was further enhanced by application of AMF, can be harnessed for on-site remediation of Pb contaminated soils. The content of Cd and As in the edible part was found to be within safe limits (HQ < 1) when compared to chronic reference dose stated by USEPA. Copyright © 2017 Elsevier Inc. All rights reserved.

Metabolic robustness in young roots underpins a predictive model of maize hybrid performance in the field.

PubMed

de Abreu E Lima, Francisco; Westhues, Matthias; Cuadros-Inostroza, Álvaro; Willmitzer, Lothar; Melchinger, Albrecht E; Nikoloski, Zoran

2017-04-01

Heterosis has been extensively exploited for yield gain in maize (Zea mays L.). Here we conducted a comparative metabolomics-based analysis of young roots from in vitro germinating seedlings and from leaves of field-grown plants in a panel of inbred lines from the Dent and Flint heterotic patterns as well as selected F 1 hybrids. We found that metabolite levels in hybrids were more robust than in inbred lines. Using state-of-the-art modeling techniques, the most robust metabolites from roots and leaves explained up to 37 and 44% of the variance in the biomass from plants grown in two distinct field trials. In addition, a correlation-based analysis highlighted the trade-off between defense-related metabolites and hybrid performance. Therefore, our findings demonstrated the potential of metabolic profiles from young maize roots grown under tightly controlled conditions to predict hybrid performance in multiple field trials, thus bridging the greenhouse-field gap. © 2017 The Authors The Plant Journal © 2017 John Wiley & Sons Ltd.

Osmotic Adjustment in Cotton (Gossypium hirsutum L.) Leaves and Roots in Response to Water Stress 1

PubMed Central

Oosterhuis, Derrick M.; Wullschleger, Stan D.

1987-01-01

The relative magnitude of adjustment in osmotic potential (ψs) of water-stressed cotton (Gossypium hirsutum L.) leaves and roots was studied using plants raised in pots of sand and grown in a growth chamber. One and three water-stress preconditioning cycles were imposed by withholding water, and the subsequent adjustment in solute potential upon relief of the stress and complete rehydration was monitored with thermocouple psychrometers. Both leaves and roots exhibited a substantial adjustment in ψs in response to water stress with the former exhibiting the larger absolute adjustment. The osmotic adjustment of leaves was 0.41 megapascal compared to 0.19 megapascal in the roots. The roots, however, exhibited much larger percentage osmotic adjustments of 46 and 63% in the one and three stress cycles, respectively, compared to 22 and 40% in the leaves in similar stress cycles. The osmotically adjusted condition of leaves and roots decreased after relief of the single cycle stress to about half the initial value within 3 days, and to the well-watered control level within 6 days. In contrast, increasing the number of water-stress preconditioning cycles resulted in significant percentage osmotic adjustment still being present after 6 days in roots but not in the leaves. The decrease in ψs of leaves persisted longer in field-grown cotton plants compared to plants of the same age grown in the growth chamber. The advantage of decreased ψs in leaves and roots of water-stressed cotton plants was associated with the maintenance of turgor during periods of decreasing water potentials. PMID:16665577

Molecular Dynamic Simulation of Space and Earth-Grown Crystal Structures of Thermostable T1 Lipase Geobacillus zalihae Revealed a Better Structure.

PubMed

Ishak, Siti Nor Hasmah; Aris, Sayangku Nor Ariati Mohamad; Halim, Khairul Bariyyah Abd; Ali, Mohd Shukuri Mohamad; Leow, Thean Chor; Kamarudin, Nor Hafizah Ahmad; Masomian, Malihe; Rahman, Raja Noor Zaliha Raja Abd

2017-09-25

Less sedimentation and convection in a microgravity environment has become a well-suited condition for growing high quality protein crystals. Thermostable T1 lipase derived from bacterium Geobacillus zalihae has been crystallized using the counter diffusion method under space and earth conditions. Preliminary study using YASARA molecular modeling structure program for both structures showed differences in number of hydrogen bond, ionic interaction, and conformation. The space-grown crystal structure contains more hydrogen bonds as compared with the earth-grown crystal structure. A molecular dynamics simulation study was used to provide insight on the fluctuations and conformational changes of both T1 lipase structures. The analysis of root mean square deviation (RMSD), radius of gyration, and root mean square fluctuation (RMSF) showed that space-grown structure is more stable than the earth-grown structure. Space-structure also showed more hydrogen bonds and ion interactions compared to the earth-grown structure. Further analysis also revealed that the space-grown structure has long-lived interactions, hence it is considered as the more stable structure. This study provides the conformational dynamics of T1 lipase crystal structure grown in space and earth condition.

Plant roots use a patterning mechanism to position lateral root branches toward available water.

PubMed

Bao, Yun; Aggarwal, Pooja; Robbins, Neil E; Sturrock, Craig J; Thompson, Mark C; Tan, Han Qi; Tham, Cliff; Duan, Lina; Rodriguez, Pedro L; Vernoux, Teva; Mooney, Sacha J; Bennett, Malcolm J; Dinneny, José R

2014-06-24

The architecture of the branched root system of plants is a major determinant of vigor. Water availability is known to impact root physiology and growth; however, the spatial scale at which this stimulus influences root architecture is poorly understood. Here we reveal that differences in the availability of water across the circumferential axis of the root create spatial cues that determine the position of lateral root branches. We show that roots of several plant species can distinguish between a wet surface and air environments and that this also impacts the patterning of root hairs, anthocyanins, and aerenchyma in a phenomenon we describe as hydropatterning. This environmental response is distinct from a touch response and requires available water to induce lateral roots along a contacted surface. X-ray microscale computed tomography and 3D reconstruction of soil-grown root systems demonstrate that such responses also occur under physiologically relevant conditions. Using early-stage lateral root markers, we show that hydropatterning acts before the initiation stage and likely determines the circumferential position at which lateral root founder cells are specified. Hydropatterning is independent of endogenous abscisic acid signaling, distinguishing it from a classic water-stress response. Higher water availability induces the biosynthesis and transport of the lateral root-inductive signal auxin through local regulation of tryptophan aminotransferase of Arabidopsis 1 and PIN-formed 3, both of which are necessary for normal hydropatterning. Our work suggests that water availability is sensed and interpreted at the suborgan level and locally patterns a wide variety of developmental processes in the root.

From Experiments to Simulations: Downscaling Measurements of Na+ Distribution at the Root-Soil Interface

NASA Astrophysics Data System (ADS)

Perelman, A.; Guerra, H. J.; Pohlmeier, A. J.; Vanderborght, J.; Lazarovitch, N.

2017-12-01

When salinity increases beyond a certain threshold, crop yield will decrease at a fixed rate, according to the Maas and Hoffman model (1976). Thus, it is highly important to predict salinization and its impact on crops. Current models do not consider the impact of the transpiration rate on plant salt tolerance, although it affects plant water uptake and thus salt accumulation around the roots, consequently influencing the plant's sensitivity to salinity. Better model parametrization can improve the prediction of real salinity effects on crop growth and yield. The aim of this research is to study Na+ distribution around roots at different scales using different non-invasive methods, and to examine how this distribution is affected by the transpiration rate and plant water uptake. Results from tomato plants that were grown on rhizoslides (a capillary paper growth system) showed that the Na+ concentration was higher at the root-substrate interface than in the bulk. Also, Na+ accumulation around the roots decreased under a low transpiration rate, supporting our hypothesis. The rhizoslides enabled the root growth rate and architecture to be studied under different salinity levels. The root system architecture was retrieved from photos taken during the experiment, enabling us to incorporate real root systems into a simulation. Magnetic resonance imaging (MRI) was used to observe correlations between root system architectures and Na+ distribution. The MRI provided fine resolution of the Na+ accumulation around a single root without disturbing the root system. With time, Na+ accumulated only where roots were found in the soil and later around specific roots. Rhizoslides allow the root systems of larger plants to be investigated, but this method is limited by the medium (paper) and the dimension (2D). The MRI can create a 3D image of Na+ accumulation in soil on a microscopic scale. These data are being used for model calibration, which is expected to enable the prediction of root water uptake in saline soils for different climatic conditions and different soil water availabilities.

Root Gravitropism: Quantification, Challenges, and Solutions.

PubMed

Muller, Lukas; Bennett, Malcolm J; French, Andy; Wells, Darren M; Swarup, Ranjan

2018-01-01

Better understanding of root traits such as root angle and root gravitropism will be crucial for development of crops with improved resource use efficiency. This chapter describes a high-throughput, automated image analysis method to trace Arabidopsis (Arabidopsis thaliana) seedling roots grown on agar plates. The method combines a "particle-filtering algorithm with a graph-based method" to trace the center line of a root and can be adopted for the analysis of several root parameters such as length, curvature, and stimulus from original root traces.

Proteomic analysis of Populus × euramericana (clone I-214) roots to identify key factors involved in zinc stress response.

PubMed

Romeo, Stefania; Trupiano, Dalila; Ariani, Andrea; Renzone, Giovanni; Scippa, Gabriella S; Scaloni, Andrea; Sebastiani, Luca

2014-07-15

Contamination of soil and water by heavy metals has become a widespread problem; environmental pollution by high zinc (Zn) concentration occurs frequently. Although poplar (Populus spp.) has been identified as suitable for phytoremediation approaches, its response to high Zn concentrations are still not clearly understood. For this reason, we investigated the effects of Zn in Populus×euramericana clone I-214 roots by proteomic analysis. Comparative experiments were conducted on rooted woody cuttings grown in nutrient solutions containing 1mM (treatment) or 1μM (control) Zn concentrations. A gel-based proteomic approach coupled with morphological and chemical analysis was used to identify differentially represented proteins in treated roots and to investigate the effect of Zn treatment on the poplar root system. Data shows that Zn was accumulated preferentially in roots, that the antioxidant system, the carbohydrate/energy and amino acid metabolisms were the main pathways modulated by Zn excess, and that mitochondria and vacuoles were the cellular organelles predominately affected by Zn stress. A coordination between cell death and proliferation/growth seems to occur under this condition to counteract the Zn-induced damage. Copyright © 2014 Elsevier GmbH. All rights reserved.

Influence of microgravity on cellular differentiation in root caps of Zea mays

NASA Technical Reports Server (NTRS)

Moore, R.; Fondren, W. M.; McClelen, C. E.; Wang, C. L.

1987-01-01

We launched imbibed seeds of Zea mays into outer space aboard the space shuttle Columbia to determine the influence of microgravity on cellular differentiation in root caps. The influence of microgravity varied with different stages of cellular differentiation. Overall, microgravity tended to 1) increase relative volumes of hyaloplasm and lipid bodies, 2) decrease the relative volumes of plastids, mitochondria, dictyosomes, and the vacuome, and 3) exert no influence on the relative volume of nuclei in cells comprising the root cap. The reduced allocation of dictyosomal volume in peripheral cells of flight-grown seedlings correlated positively with their secretion of significantly less mucilage than peripheral cells of Earth-grown seedlings. These results indicate that 1) microgravity alters the patterns of cellular differentiation and structures of all cell types comprising the root cap, and 2) the influence of microgravity on cellular differentiation in root caps of Zea mays is organelle specific.

Arbuscular mycorrhizal fungal hyphae contribute to the uptake of polycyclic aromatic hydrocarbons by plant roots.

PubMed

Gao, Yanzheng; Cheng, Zhaoxia; Ling, Wanting; Huang, Jing

2010-09-01

The arbuscular mycorrhizal (AM) hyphae-mediated uptake of polycyclic aromatic hydrocarbons (PAHs) by the roots of ryegrass (Lolium multiflorum Lam.) was investigated using three-compartment systems. Glomus mosseae and Glomus etunicatum were chosen, and fluorene and phenanthrene were used as representative PAHs. When roots were grown in un-spiked soils, AM hyphae extended into PAH-spiked soil and clearly absorbed and transported PAHs to roots, resulting in high concentrations of fluorene and phenanthrene in roots. This was further confirmed by the batch equilibration experiment, which revealed that the partition coefficients (K(d)) of tested PAHs by mycorrhizal hyphae were 270-356% greater than those by roots, suggesting the great potential of hyphae to absorb PAHs. Because of fluorene's lower molecular weight and higher water solubility, its translocation by hyphae was greater than that of phenanthrene. These results provide new perspectives on the AM hyphae-mediated uptake by plants of organic contaminants from soil. Copyright 2010 Elsevier Ltd. All rights reserved.

Biological activities and chemical composition of the stems and roots of Helichrysum oligocephalum DC grown in Iran.

PubMed

Esmaeili, Akbar

2013-05-01

Helichrysum has long been used medicinally, proving to be beneficial in treatment of acne, asthma, bronchitis and circulatory problems, and lymphatic system diseases. The objective of this research was to study the antioxidant and antibacterial activities and chemical composition of the compounds derived from the stems and roots of cultivated H. oligocephalum using gas chromatography (GC) and gas chromatography-mass spectroscopy (GC-MS). The primary components found in the stem oil were ortho-vanillin (51.0%) and carvacrol (16.0%), and those found in the root oil were 1,8-cineole (30.6%) and isobornyl acetate (13.9%). Stem and root oils of H. oligocephalum demonstrated antibacterial activity, particularly in relation to Gram-positive bacteria. In a β-carotene/linoleic acid bleaching assay, the root oil of H. oligocephalum demonstrated an antioxidant effect. Antioxidant capacity measured with 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay was 1205.0 for the stem oil and 722.8 μg/ml for the root oil.

Operationally Defined Apoplastic and Symplastic Aluminum Fractions in Root Tips of Aluminum-Intoxicated Wheat

PubMed Central

Tice, Kathy R.; Parker, David R.; DeMason, Darleen A.

1992-01-01

Knowledge of the mechanistic basis of differential aluminum (Al) tolerance depends, in part, on an improved ability to quantify Al located in the apoplastic and symplastic compartments of the root apex. Using root tips excised from seedlings of an Al-tolerant wheat cultivar (Triticum aestivum L. cv Yecora Rojo) grown in Al solutions for 2 d, we established an operationally defined apoplastic Al fraction determined with six sequential 30-min washes using 5 mm CaCl2 (pH 4.3). Soluble symplastic Al was eluted by freezing root tips to rupture cell membranes and performing four additional 30-min CaCl2 washes, and a residual fraction was determined via digestion of root tips with HNO3. The three fractions were then determined in Yecora Rojo and a sensitive wheat cultivar (Tyler) grown at 18, 55, or 140 μm total solution Al (AlT). When grown at equal AlT, Tyler contained more Al than Yecora Rojo in all fractions, but both total Al and fractional distribution were similar in the two cultivars grown at AlT levels effecting a 50% reduction in root growth. Residual Al was consistently 50 to 70% of the total, and its location was elucidated by staining root tips with the fluorophore morin and examining them using fluorescence and confocal laser scanning microscopy. Wall-associated Al was only observed in tips prior to any washing, and the residual fraction was manifested as distinct staining of the cytoplasm and nucleus but not of the apoplastic space. Accordingly, the residual fraction was allocated to the symplastic compartment for both cultivars, and recalculated apoplastic Al was consistently approximately 30 to 40% of the total. Distributions of Al in the two cultivars did not support a symplastic detoxification hypothesis, but the role of cytoplasmic exclusion remains unsettled. Images Figure 4 Figure 5 PMID:16652962

Plant Bio-Wars: Maize Protein Networks Reveal Tissue-Specific Defense Strategies in Response to a Root Herbivore.

PubMed

Castano-Duque, Lina; Helms, Anjel; Ali, Jared Gregory; Luthe, Dawn S

2018-06-21

In this study we examined global changes in protein expression in both roots and leaves of maize plants attacked by the root herbivore, Western corn rootworm (WCR, Diabrotica virgifera virgifera). The changes in protein expression Are indicative of metabolic changes during WCR feeding that enable the plant to defend itself. This is one of the first studies to look above- and below-ground at global protein expression patterns of maize plants grown in soil and infested with a root herbivore. We used advanced proteomic and network analyses to identify metabolic pathways that contribute to global defenses deployed by the insect resistant maize genotype, Mp708, infested with WCR. Using proteomic analysis, 4878 proteins in roots and leaves were detected and of these 863 showed significant changes of abundance during WCR infestation. Protein abundance patterns were analyzed using hierarchical clustering, protein correlation and protein-protein interaction networks. All three data analysis pipelines showed that proteins such as jasmonic acid biosynthetic enzymes, serine proteases, protease inhibitors, proteins involved in biosynthesis and signaling of ethylene, and enzymes producing reactive oxygen species and isopentenyl pyrophosphate, a precursor for volatile production, were upregulated in roots during WCR infestation. In leaves, highly abundant proteins were involved in signal perception suggesting activation of systemic signaling. We conclude that these protein networks contribute to the overall herbivore defense mechanisms in Mp708. Because the plants were grown in potting mix and not sterilized sand, we found that both microbial and insect defense-related proteins were present in the roots. The presence of the high constitutive levels of reduced ascorbate in roots and benzothiazole in the root volatile profiles suggest a tight tri-trophic interaction among the plant, soil microbiomes and WCR-infested roots suggesting that defenses against insects coexist with defenses against bacteria and fungi due to the interaction between roots and soil microbiota. In this study, which is one of the most complete descriptions of plant responses to root-feeding herbivore, we established an analysis pipeline for proteomics data that includes network biology that can be used with different types of "omics" data from a variety of organisms.

The Use of Arbuscular Mycorrhizal Fungi to Improve Strawberry Production in Coir Substrate

PubMed Central

Robinson Boyer, Louisa; Feng, Wei; Gulbis, Natallia; Hajdu, Klara; Harrison, Richard J.; Jeffries, Peter; Xu, Xiangming

2016-01-01

Strawberry is an important fruit crop within the UK. To reduce the impact of soil-borne diseases and extend the production season, more than half of the UK strawberry production is now in substrate (predominantly coir) under protection. Substrates such as coir are usually depleted of microbes including arbuscular mycorrhizal fungi (AMF) and consequently the introduction of beneficial microbes is likely to benefit commercial cropping systems. Inoculating strawberry plants in substrate other than coir has been shown to increase plants tolerance to soil-borne pathogens and water stress. We carried out studies to investigate whether AMF could improve strawberry production in coir under low nitrogen input and regulated deficit irrigation. Application of AMF led to an appreciable increase in the size and number of class I fruit, especially under either deficient irrigation or low nitrogen input condition. However, root length colonization by AMF was reduced in strawberry grown in coir compared to soil and Terragreen. Furthermore, the appearance of AMF colonizing strawberry and maize roots grown in coir showed some physical differences from the structure in colonized roots in soil and Terragreen: the colonization structure appeared to be more compact and smaller in coir. PMID:27594859

SEASONAL CHANGES IN ROOT AND SOIL RESPIRATION OF OZONE-EXPOSED PONDEROSA PINE (PINUS PONDEROSA) GROWN IN DIFFERENT SUBSTRATES

EPA Science Inventory

Exposure to(ozone 0-3)has been shown to decrease the allocation of carbon to tree roots. Decreased allocation of carbon to roots might disrupt root metabolism and rhizosphere organisms. The effects of soil type and shoot 0, exposure on below-ground respiration and soil microbial ...

Naturally developed seedling roots of five western conifers.

Treesearch

William I. Stein

1978-01-01

Two-year-old seedlings grown from seed outdoors in three southwestern Oregon soils were excavated to determine their root development. Roots of Douglas-fir, ponderosa pine, sugar pine, grand fir, and incense-cedar seedlings differed substantially in total extent, form, and balance in relation to tops. Information on the natural development of roots provides a benchmark...

Influence of cultural practices on edaphic factors related to root disease in Pinus nursery seedlings

Treesearch

J Juzwik; K. M. Gust; R. R. Allmaras

1999-01-01

Conifer seedlings grown in bare-root nurseries are frequently damaged and destroyed by soil-borne pathogenic fungi that cause root rot. Relationships between nursery cultural practices, soils characteristics, and populations of potential pathogens in the soil were examined in three bare-root tree nurseries in the midwestern USA. Soil-borne populations of ...

Soil temperature and precipitation affect the rooting ability of dormant hardwood cuttings of Populus

Treesearch

R.S., Jr. Zalesny; R.B. Hall; E.O. Bauer; D.E. Riemenschneider

2005-01-01

In addition to genetic control, responses to environmental stimuli affect the success of rooting. Our objectives were to: 1) assess the variation in rooting ability among 21 Populus clones grown under varying soil temperatures and amounts of precipitation and 2) identify combinations of soil temperature and precipitation that promote rooting. The...

Do root traits affect a plant's ability to influence soil erosion?

NASA Astrophysics Data System (ADS)

Burak, Emma; Quinton, John; Dodd, Ian

2017-04-01

With the ever increasing global population the agricultural sector is put under increasing pressure. This pressure is imposed on the soil and results in wide spread degradation that ultimately decreases productivity. Soil erosion is one of the main features of this degradation. Much focus has been put on the ability of plant canopies to mitigate soil erosion but little research has assessed the impact of below ground biomass. It is understood that woody roots reinforce slopes and lateral roots are believed to support the soil surface but the impact of root hairs is completely unknown. This study used two root hairless mutants one of barley (brb) and one of maize (rth3) along with their wild types (WT) to assess the capacity of different root traits to bind soil particles to the root system, creating a physical coating called a rhizosheath. The two genotypes were grown in a clay loam and periodically harvested during vegetative development. Rhizosheath weight was used to measure the ability of the root system to effectively bind soil particles, while root length was measured to standardise the results between genotypes. Overall, rhizosheath weight increased linearly with root length. When compared to WT plants of the same age, the root length of brb was, on average, 37% greater, suggesting that they compensated for the absence of root hairs by proliferating lateral roots. However, WT plants were far superior at binding soil particles as the rhizosheath weights were 5 fold greater, when expressed per unit root length. Thus root hairs are more important in binding soil particles than lateral roots. Whether these genotypic differences in root traits affect soil erosion will be assessed using mesocosm and field trials. Keywords: Soil erosion, Roots, Barley, Rhizosheath

Domestication and Crop Physiology: Roots of Green-Revolution Wheat

PubMed Central

Waines, J. Giles; Ehdaie, Bahman

2007-01-01

Background and Aims Most plant scientists, in contrast to animal scientists, study only half the organism, namely above-ground stems, leaves, flowers and fruits, and neglect below-ground roots. Yet all acknowledge roots are important for anchorage, water and nutrient uptake, and presumably components of yield. This paper investigates the relationship between domestication, and the root systems of landraces, and the parents of early, mid- and late green-revolution bread wheat cultivars. It compares the root system of bread wheat and ‘Veery’-type wheat containing the 1RS translocation from rye. Methods Wheat germplasm was grown in large pots in sand culture in replicated experiments. This allowed roots to be washed free to study root characters. Key Results The three bread wheat parents of early green-revolution wheats have root biomass less than two-thirds the mean of some landrace wheats. Crossing early green-revolution wheat to an F2 of ‘Norin 10’ and ‘Brevor’, further reduced root biomass in mid-generation semi-dwarf and dwarf wheats. Later-generation semi-dwarf wheats show genetic variation for root biomass, but some exhibit further reduction in root size. This is so for some California and UK wheats. The wheat–rye translocation in ‘Kavkaz’ for the short arm of chromosome 1 (1RS) increased root biomass and branching in cultivars that contained it. Conclusions Root size of modern cultivars is small compared with that of landraces. Their root system may be too small for optimum uptake of water and nutrients and maximum grain yield. Optimum root size for grain yield has not been investigated in wheat or most crop plants. Use of 1RS and similar alien translocations may increase root biomass and grain yield significantly in irrigated and rain-fed conditions. Root characters may be integrated into components of yield analysis in wheat. Plant breeders may need to select directly for root characters. PMID:17940075

A continuous culture system of direct somatic embryogenesis in microspore-derived embryos of Brassica juncea.

PubMed

Prabhudesai, V; Bhaskaran, S

1993-03-01

An efficient culture system has been developed for repeated cycles of somatic embryogenesis in microspore-derived embryos of Brassica juncea without a callus phase. Haploid embryos produced through anther culture showed a high propensity for direct production of somatic embryos in response to 2 mgL(-1) BA and 0.1 mgL(-1) NAA. The embryogenic cultures which comprised the elongated embryonal axis of microspore-derived embryos when explanted and grown on the medium of same composition produced a large number of secondary embryos. These somatic embryos in turn underwent axis elongation and produced more somatic embryos when explanted and cultured. This cycle of repetitive somatic embryogenesis continued with undiminished vigour passage after passage and was monitored for more than a year. Somatic embryos from any passage when isolated at cotyledonary stage and grown on auxin-free medium for 5 days and then on a medium containing NAA (0.1 mgL(-1)), developed into complete plants with a profuse root system and were easily established in the soil. The cytology of the root tips of these plants confirmed their haploid nature. The total absence of callus phase makes the system ideal for continuous cloning of androgenic lines, Agrobacterium-mediated transformation and mutation induction studies.

Root restriction: A tool for improving volume utilization efficiency in bioregenerative life-support systems

NASA Astrophysics Data System (ADS)

Graham, Thomas; Wheeler, Raymond

2016-06-01

The objective of this study was to evaluate root restriction as a tool to increase volume utilization efficiency in spaceflight crop production systems. Bell pepper plants (Capsicum annuum cv. California Wonder) were grown under restricted rooting volume conditions in controlled environment chambers. The rooting volume was restricted to 500 ml and 60 ml in a preliminary trial, and 1500 ml (large), 500 ml (medium), and 250 ml (small) for a full fruiting trial. To reduce the possible confounding effects of water and nutrient restrictions, care was taken to ensure an even and consistent soil moisture throughout the study, with plants being watered/fertilized several times daily with a low concentration soluble fertilizer solution. Root restriction resulted in a general reduction in biomass production, height, leaf area, and transpiration rate; however, the fruit production was not significantly reduced in the root restricted plants under the employed environmental and horticultural conditions. There was a 21% reduction in total height and a 23% reduction in overall crown diameter between the large and small pot size in the fruiting study. Data from the fruiting trial were used to estimate potential volume utilization efficiency improvements for edible biomass in a fixed production volume. For fixed lighting and rooting hardware situations, the majority of improvement from root restriction was in the reduction of canopy area per plant, while height reductions could also improve volume utilization efficiency in high stacked or vertical agricultural systems.

Root restriction: A tool for improving volume utilization efficiency in bioregenerative life-support systems.

PubMed

Graham, Thomas; Wheeler, Raymond

2016-06-01

The objective of this study was to evaluate root restriction as a tool to increase volume utilization efficiency in spaceflight crop production systems. Bell pepper plants (Capsicum annuum cv. California Wonder) were grown under restricted rooting volume conditions in controlled environment chambers. The rooting volume was restricted to 500ml and 60ml in a preliminary trial, and 1500ml (large), 500ml (medium), and 250ml (small) for a full fruiting trial. To reduce the possible confounding effects of water and nutrient restrictions, care was taken to ensure an even and consistent soil moisture throughout the study, with plants being watered/fertilized several times daily with a low concentration soluble fertilizer solution. Root restriction resulted in a general reduction in biomass production, height, leaf area, and transpiration rate; however, the fruit production was not significantly reduced in the root restricted plants under the employed environmental and horticultural conditions. There was a 21% reduction in total height and a 23% reduction in overall crown diameter between the large and small pot size in the fruiting study. Data from the fruiting trial were used to estimate potential volume utilization efficiency improvements for edible biomass in a fixed production volume. For fixed lighting and rooting hardware situations, the majority of improvement from root restriction was in the reduction of canopy area per plant, while height reductions could also improve volume utilization efficiency in high stacked or vertical agricultural systems. Copyright © 2016 The Committee on Space Research (COSPAR). All rights reserved.

On the use of antibiotics to reduce rhizoplane microbial populations in root physiology and ecology investigations

NASA Technical Reports Server (NTRS)

Smart, D. R.; Ferro, A.; Ritchie, K.; Bugbee, B. G.

1995-01-01

No straightforward method exists for separating the proportion of ion exchange and respiration due to rhizoplane microbial organisms from that of root ion exchange and respiration. We examined several antibiotics that might be used for the temporary elimination of rhizoplane bacteria from hydroponically grown wheat roots (Triticum aestivum cv. Veery 10). Each antibiotic was tested for herbicidal activity and plate counts were used to enumerate bacteria and evaluate antibiotic kinetics. Only lactam antibiotics (penicillins and cephalosporins) did not reduce wheat growth rates. Aminoglycosides, the pyrimidine trimethoprim, colistin and rifampicin reduced growth rates substantially. Antibiotics acted slowly, with maximum reductions in rhizoplane bacteria occurring after more than 48 h of exposure. Combinations of nonphytotoxic antibiotics reduced platable rhizoplane bacteria by as much as 98%; however, this was generally a reduction from about 10(9) to 10(6) colony forming units per gram of dry root mass, so that many viable bacteria remained on root surfaces. We present evidence which suggests that insufficient bacterial biomass exists on root surfaces of nonstressed plants grown under well-aerated conditions to quantitatively interfere with root nitrogen absorption measurements.

Establishment of in vitro adventitious root cultures and analysis of andrographolide in Andrographis paniculata.

PubMed

Sharma, Shiv Narayan; Jha, Zenu; Sinha, Rakesh Kumar

2013-08-01

Andrographolide is the principal bioactive component of the medicinal plant Andrographis paniculata, to which various diverse pharmacological properties are attributed. Traditionally, andrographolide was extracted from the leaves, stems and other parts of the plant. Leaves have the highest andrographolide content (2-3%) in comparison with the other plant parts. Adventitious root culture of leaf explants of A. paniculata was studied using different strength MS medium supplemented by different concentrations of auxins and a combination of NAA + kinetin for growth and andrographolide production. Among the different auxin treatments in adventitious root culture, only NAA was able to induce adventitious roots. Adventitious roots grown in modified strength MS medium showed the highest root growth (26.7 +/- 1.52), as well as the highest amount of andrographolide (133.3 +/- 1.5 mg/g DW) as compared with roots grown in half- and full-strength MS medium. Growth kinetics showed maximum biomass production after five weeks of culture in different strength MS liquid medium. The produced andrographolide content was 3.5 - 5.5 folds higher than that of the natural plant, depending on the medium strength.

A Normative Approach to the Legitimacy of Muslim Schools in Multicultural Britain

ERIC Educational Resources Information Center

Hills, Peter Matthew

2015-01-01

Debate has grown about the legitimacy of Muslim faith schools within the British education system. At the same time, scepticism has developed towards multiculturalism as a normative approach for dealing with diversity. This article argues that it is worth retaining the normative impetus of multiculturalism by returning to its roots in political…

Adaptive Management Tools for Nitrogen: Nitrogen Index, Nitrogen Trading Tool and Nitrogen Losses Environmental Assessment Package (NLEAP-GIS)

USDA-ARS?s Scientific Manuscript database

Average nitrogen (N) use efficiencies are approximately fifty percent and can be even lower for shallower rooted systems grown on irrigated sandy soils. These low N use efficiencies need to be increased if reactive N losses to the environmental are to be reduced. Recently, USDA-NRCS identified Adapt...

In situ sensors, weighing lysimeters and COSMOS under vegetated and bare conditions with subsurface drip irrigation

USDA-ARS?s Scientific Manuscript database

Long term weighing lysimeter records may have utility for assessment of climate changes occurring during the period of record. They typically enclose a depth of soil that exceeds the root zone of vegetation normally grown on them and have drainagy systems so that more or less natural hydrologic flux...

Belowground impacts of perennial grass cultivation for sustainable biofuel feedstock production in the tropics

DOE PAGES

Sumiyoshi, Yudai; Crow, Susan E.; Litton, Creighton M.; ...

2016-07-08

Perennial grasses can sequester soil organic carbon (SOC) in sustainably managed biofuel systems, directly mitigating atmospheric CO 2 concentrations while simultaneously generating biomass for renewable energy. Our objective was to quantify SOC accumulation and identify the primary drivers of belowground C dynamics in a zero-tillage production system of tropical perennial C4 grasses grown for biofuel feedstock in Hawaii. Specifically, the quantity, quality, and fate of soil C inputs were determined for eight grass accessions – four varieties each of napier grass and guinea grass. Carbon fluxes (soil CO 2 efflux, aboveground net primary productivity, litterfall, total belowground carbon flux, rootmore » decay constant), C pools (SOC pool and root biomass), and C quality (root chemistry, C and nitrogen concentrations, and ratios) were measured through three harvest cycles following conversion of a fallow field to cultivated perennial grasses. A wide range of SOC accumulation occurred, with both significant species and accession effects. Aboveground biomass yield was greater, and root lignin concentration was lower for napier grass than guinea grass. Structural equation modeling revealed that root lignin concentration was the most important driver of SOC pool: varieties with low root lignin concentration, which was significantly related to rapid root decomposition, accumulated the greatest amount of SOC. Roots with low lignin concentration decomposed rapidly, but the residue and associated microbial biomass/by-products accumulated as SOC. In general, napier grass was better suited for promoting soil C sequestration in this system. Further, high-yielding varieties with low root lignin concentration provided the greatest climate change mitigation potential in a ratoon system. By understanding the factors affecting SOC accumulation and the net greenhouse gas trade-offs within a biofuel production system will aid in crop selection to meet multiple goals toward environmental and economic sustainability.« less

Biochemical and molecular characterization of rice (Oryza sativa L.) roots forming a barrier to radial oxygen loss.

PubMed

Kulichikhin, Konstantin; Yamauchi, Takaki; Watanabe, Kohtaro; Nakazono, Mikio

2014-10-01

The formation of a barrier to radial oxygen (O2 ) loss (ROL) in the root is an important adaptation of plants to root flooding, but the biochemical changes in plant roots where the barrier is formed are unclear. In this study, we analysed metabolic profiles and gene expression profiles in roots of rice (Oryza sativa L.) plants grown under stagnant deoxygenated conditions, which induce suberization in the outer cell layers of the roots and formation of barrier to ROL. Under these conditions, two distinctive biochemical features of the roots were the accumulations of malic acid and very long chain fatty acids (VLCFAs). We also showed that the expressions of some genes encoding plastid-localized enzymes, which convert malic acid to acetyl coenzyme A (AcCoA), were simultaneously up-regulated under stagnant conditions. The expression levels of these genes in specific root tissues isolated by laser microdissection suggested that malic acid is converted to AcCoA predominantly in the plastids in the outer cell layers of rice roots. We propose that the physiological role of malic acid accumulation in rice roots grown under stagnant conditions is to provide a substrate for the biosynthesis of fatty acids, which, in turn, are used in the biosynthesis of suberin. © 2014 John Wiley & Sons Ltd.

Polar transport of 45Ca2+ across the elongation zone of gravistimulated roots

NASA Technical Reports Server (NTRS)

Lee, J. S.; Evans, M. L.

1985-01-01

The movement of calcium across the elongation zone of gravistimulated primary roots of maize (Zea mays L.) was measured using 45Ca2+. Radioactive calcium was applied to one side of the elongation zone about 4 mm back from the root tip and the distribution of radioactivity across the root in the region of application was determined using scintillation spectrometry. The movement of 45Ca2+ across the elongation zone was non-polar in vertically oriented roots. In gravistimulated roots the movement of label was polarized with about twice as much label moving from top to bottom as from bottom to top. A variety of treatments which interfere with gravitropism was found to eliminate the polar movement of 45Ca2+ across the elongation zone. In maize cultivars which require light for gravitropic competency, dark grown roots exhibited neither gravitropism nor polar movement of 45Ca2+ across the elongation zone. Upon illumination the roots developed but gravitropic competency and gravity-induced polar movement of 45Ca2+ across the elongation zone. Similarly, roots of light-grown seedlings lost both gravitropic competency and 45Ca2+ transport polarity upon transfer to the dark. The results indicate a close correlation between calcium movement and gravitropism in primary roots in maize.

Perception of neighboring plants by rhizomes and roots: morphological manifestations of a clonal plant

USGS Publications Warehouse

Huber-Sannwald, Elisabeth; Pyke, David A.; Caldwell, M.M.

1997-01-01

A previous study showed that clonal morphology of the rhizomatous grass Elymus lanceolatus ssp. lanceolatus (Scibner & J.G. Smith Gould) was influenced more by neighbouring root systems than by the local distribution of nutrients. In this study we determine whether individual rhizomes or roots of E. lanceolatus perceive neighbouring root systems and how this is manifested in morphological responses of E. lanceolatus clones. Elymus lanceolatus was grown in the same bin with Pseudoroegneria spicata (Pursh) A. Love or Agropyron desertorum (Fisch. ex Link) Schult. plants. Elymus lanceolatus was separated from its neighbours by different barriers. The barriers allowed either only E. lanceolatus roots; only a single E. lanceolatus primary rhizome; or both roots and rhizomes to contact the neighbour root system. When only a single E. lanceolatus primary rhizome with potentially developing branching rhizomes made contact with the neighbour, the clonal structure of E. lanceolatus was modified more with P. spicata as the neighbour than with A. desertorum. With root contact of E. lanceolatus alone there was a similar effect with the neighbouring plants, but there was a more marked inhibitory effect on E. lanceolatus clonal growth with P. spicata than with A. desertorum, compared with the treatment with only a single rhizome in contact with the neighbour. Root resource competition in the unconstrained treatment (roots and rhizomes) between neighbouring plant and E. lanceolatus was more apparent with A. desertorum than with P. spicata. This study is one of the first to document that rhizome and root contact of a clonal plant with its neighbours may induce different clonal responses depending on the species of neighbour.

The role of strigolactones in photomorphogenesis of pea is limited to adventitious rooting.

PubMed

Urquhart, Shelley; Foo, Eloise; Reid, James B

2015-03-01

The recently discovered group of plant hormones, the strigolactones, have been implicated in regulating photomorphogenesis. We examined this extensively in our strigolactone synthesis and response mutants and could find no evidence to support a major role for strigolactone signaling in classic seedling photomorphogenesis (e.g. elongation and leaf expansion) in pea (Pisum sativum), consistent with two recent independent reports in Arabidopsis. However, we did find a novel effect of strigolactones on adventitious rooting in darkness. Strigolactone-deficient mutants, Psccd8 and Psccd7, produced significantly fewer adventitious roots than comparable wild-type seedlings when grown in the dark, but not when grown in the light. This observation in dark-grown plants did not appear to be due to indirect effects of other factors (e.g. humidity) as the constitutively de-etiolated mutant, lip1, also displayed reduced rooting in the dark. This role for strigolactones did not involve the MAX2 F-Box strigolactone response pathway as Psmax2 f-box mutants did not show a reduction in adventitious rooting in the dark compared with wild-type plants. The auxin-deficient mutant bushy also reduced adventitious rooting in the dark, as did decapitation of wild-type plants. Rooting was restored by the application of indole-3-acetic acid (IAA) to decapitated plants, suggesting a role for auxin in the rooting response. However, auxin measurements showed no accumulation of IAA in the epicotyls of wild-type plants compared with the strigolactone synthesis mutant Psccd8, suggesting that changes in the gross auxin level in the epicotyl are not mediating this response to strigolactone deficiency. © 2014 Scandinavian Plant Physiology Society.

The RCN1-encoded A subunit of protein phosphatase 2A increases phosphatase activity in vivo

NASA Technical Reports Server (NTRS)

Deruere, J.; Jackson, K.; Garbers, C.; Soll, D.; Delong, A.; Evans, M. L. (Principal Investigator)

1999-01-01

Protein phosphatase 2A (PP2A), a heterotrimeric serine/threonine-specific protein phosphatase, comprises a catalytic C subunit and two distinct regulatory subunits, A and B. The RCN1 gene encodes one of three A regulatory subunits in Arabidopsis thaliana. A T-DNA insertion mutation at this locus impairs root curling, seedling organ elongation and apical hypocotyl hook formation. We have used in vivo and in vitro assays to gauge the impact of the rcn1 mutation on PP2A activity in seedlings. PP2A activity is decreased in extracts from rcn1 mutant seedlings, and this decrease is not due to a reduction in catalytic subunit expression. Roots of mutant seedlings exhibit increased sensitivity to the phosphatase inhibitors okadaic acid and cantharidin in organ elongation assays. Shoots of dark-grown, but not light-grown seedlings also show increased inhibitor sensitivity. Furthermore, cantharidin treatment of wild-type seedlings mimics the rcn1 defect in root curling, root waving and hypocotyl hook formation assays. In roots of wild-type seedlings, RCN1 mRNA is expressed at high levels in root tips, and accumulates to lower levels in the pericycle and lateral root primordia. In shoots, RCN1 is expressed in the apical hook and the basal, rapidly elongating cells in etiolated hypocotyls, and in the shoot meristem and leaf primordia of light-grown seedlings. Our results show that the wild-type RCN1-encoded A subunit functions as a positive regulator of the PP2A holoenzyme, increasing activity towards substrates involved in organ elongation and differential cell elongation responses such as root curling.

Analysis of root reinforcement of vegetated riprap

NASA Astrophysics Data System (ADS)

Tron, Stefania; Raymond, Pierre

2014-05-01

Riprap is a traditional engineering solution used to protect riverbanks against erosion on developed riparian corridors. However, the traditional riprap does not provide adequate fish and wildlife habitat within the riparian zone, which is normally provided by naturally vegetated stream banks. An innovative approach, which mitigates this issue and at the same time provides stream bank erosion control, is the vegetated riprap technique. This solution, which combines rocks and native vegetation in the form of live cuttings, has been designed and implemented by Terra Erosion Control Ltd for the past 7 years. The aim of this work was to study the effect of the vegetation, in particular the root system, on the stability of the riprap. This analysis was carried out in the late spring of 2013 on the vegetated riprap installation located along the Columbia River riverbank, adjacent to the Teck Metals Ltd. smelter in Trail, British Columbia, Canada. An excavation perpendicular to the river was performed in order to investigate the root system development within the vegetated riprap structure. This excavation exposed one of the Salix bebbiana cuttings installed in 2006. The cutting was 2.3 m long and was set with an inclination of 35° with respect to the horizontal plane: the first 0.3 m was exposed, 1 m was buried within the riprap rocks (which had an average diameter of 30 cm) and the remaining 1.0 m was in the soil matrix below the rocks. The diameter of the roots growing along the cutting were measured in order to obtain the root density at various depths and tensile strength tests were carried out on the Salix bebbiana roots with diameters of up to 9 mm. The aim was to quantitatively estimate the additional cohesion given by the roots. The additional root cohesion was more effective in the deeper soil layer where the soil matrix predominates. In the upper soil layer, where the particle size is significantly higher, roots do not increase the cohesion but act as a network which ties the rocks of the riprap structure together. The uprooting resistance was also tested with a pullout test, which demonstrated that the force necessary to uproot a Salix bebianna cutting, grown in the riprap along the riverbank, was higher if compared with the same species grown in a natural environment.

Sugar Beet, Energy Beet, and Industrial Beet

USDA-ARS?s Scientific Manuscript database

Sugar beet (Beta vulgaris) is a temperate root crop grown primarily as a source of sucrose for human diets. Breeding has focused on sucrose yield, which is simply the product of total root yield times the proportion of sucrose in the harvested roots, minus loss of sucrose in molasses due to impuriti...

Aluminium tolerance of root hairs underlies genotypic differences in rhizosheath size of wheat (Triticum aestivum) grown on acid soil.

PubMed

Delhaize, Emmanuel; James, Richard A; Ryan, Peter R

2012-08-01

We found significant genetic variation in the ability of wheat (Triticum aestivum) to form rhizosheaths on acid soil and assessed whether differences in aluminium (Al(3+) ) tolerance of root hairs between genotypes was the physiological basis for this genetic variation. A method was developed to rapidly screen rhizosheath size in a range of wheat genotypes. Backcrossed populations were generated from cv Fronteira (large rhizosheath) using cv EGA-Burke (small rhizosheath) as the recurrent parent. A positive correlation existed between rhizosheath size on acid soil and root hair length. In hydroponic experiments, root hairs of the backcrossed lines with large rhizosheaths were more tolerant of Al(3+) toxicity than the backcrossed lines with small rhizosheaths. We conclude that greater Al(3+) tolerance of root hairs underlies the larger rhizosheath of wheat grown on acid soil. Tolerance of the root hairs to Al(3+) was largely independent of the TaALMT1 gene which suggests that different genes encode the Al(3+) tolerance of root hairs. The maintenance of longer root hairs in acid soils is important for the efficient uptake of water and nutrients. © 2012 The Authors. New Phytologist © 2012 New Phytologist Trust.

Distribution of withaferin A, an anticancer potential agent, in different parts of two varieties of Withania somnifera (L.) Dunal. grown in Sri Lanka.

PubMed

Siriwardane, A S; Dharmadasa, R M; Samarasinghe, Kosala

2013-02-01

Withania somnifera (L.) Dunal. (Family: Solanaceae) is a therapeutically important medicinal plant in traditional and Ayurveda systems of medicine in Sri Lanka. Witheferin A, is a potential anticancer compound found in W. somnifera. In the present study, attempts have been made to compare witheferin A content, in different parts of (root, stem, bark, leaf) two varieties of (LC1 and FR1) W. somnifera grown in same soil and climatic conditions. Ground sample (1g) of leaves, bark, stem and roots of two W. somnifera varieties were extracted with CHCl3 three times. Thin Layer Chromatographic analysis (TLC) of withaferin A in both plant extracts were performed on pre-coated Silica gel 60 GF254 plates in hexane: ethyl acetate: methanol (2: 14: 1) mobile phase. Densitometer scanning was performed at lambda(max) = 215 nm. HPLC of W. somnifera extracts was performed using Kromasil C18 reverse phase column. Both varieties of W. somnifera differed in withaferin A. After visualizing TLC plates with vanillin-sulphuric acid leaf and bark extracts of both varieties showed high intensity purple colour spots (R(f) 0.14) than in stem and roots. The highest amount of withaferin A (3812 ppm) was observed in leaves of variety LC1 while the lowest amount was observed in roots of variety FR1 (5 ppm). According to the results it could be concluded that content of Witheferin A was vary leaf > bark > stem > roots in both varieties. Therefore, there is a high potential of incorporation of leaves and bark of W. somnifera for the preparation of Ayurveda drug leading to anticancer activity instead of roots.

Understanding Aquatic Rhizosphere Processes Through Metabolomics and Metagenomics Approach

NASA Astrophysics Data System (ADS)

Lee, Yong Jian; Mynampati, Kalyan; Drautz, Daniela; Arumugam, Krithika; Williams, Rohan; Schuster, Stephan; Kjelleberg, Staffan; Swarup, Sanjay

2013-04-01

The aquatic rhizosphere is a region around the roots of aquatic plants. Many studies focusing on terrestrial rhizosphere have led to a good understanding of the interactions between the roots, its exudates and its associated rhizobacteria. The rhizosphere of free-floating roots, however, is a different habitat that poses several additional challenges, including rapid diffusion rates of signals and nutrient molecules, which are further influenced by the hydrodynamic forces. These can lead to rapid diffusion and complicates the studying of diffusible factors from both plant and/or rhizobacterial origins. These plant systems are being increasingly used for self purification of water bodies to provide sustainable solution. A better understanding of these processes will help in improving their performance for ecological engineering of freshwater systems. The same principles can also be used to improve the yield of hydroponic cultures. Novel toolsets and approaches are needed to investigate the processes occurring in the aquatic rhizosphere. We are interested in understanding the interaction between root exudates and the complex microbial communities that are associated with the roots, using a systems biology approach involving metabolomics and metagenomics. With this aim, we have developed a RhizoFlowCell (RFC) system that provides a controlled study of aquatic plants, observed the root biofilms, collect root exudates and subject the rhizosphere system to changes in various chemical or physical perturbations. As proof of concept, we have used RFC to test the response of root exudation patterns of Pandanus amaryllifolius after exposure to the pollutant naphthalene. Complexity of root exudates in the aquatic rhizosphere was captured using this device and analysed using LC-qTOF-MS. The highly complex metabolomic profile allowed us to study the dynamics of the response of roots to varying levels of naphthalene. The metabolic profile changed within 5mins after spiking with 20mg/L of naphthalene and reached a new steady state within 72 hours. An active microbial biofilm was formed during this process, which was imaged by light microscopy and confocal laser scanning microscopy and showed active changes in the biofilm. We have begun to unravel the complexity of rhizobacterial communities associated with aquatic plants. Using fluorescence in-situ hybridization (FISH) and Illumina Miseq Next Generation Sequencing of metagenomic DNA, we investigated the root-associated microbial community of P. amaryllifolius grown in two different water sources. The community structure of rhizobacteria from plants grown in freshwater lake or rainwater stored in tanks are highly similar. The top three phyla in both setups belonged to Proteobacteria, Bacteriocedes and Actinobacteria, as validated by FISH analyses. This suggests that the rhizosphere have an innate ability to attract and recruit rhizobacterial communities, possibly through the metabolic compounds secreted through root exudation. The selection pressure through plant host is higher compared to environmental pressures that are different between the two water sources. In comparison with the terrestrial rhizosphere, the aquatic rhizosphere microbiome seems more specialised and has a high influence by the host. We are using these findings to further understand the role of microbes in the performance of freshwater aquatic plants.

Nucleolus in clinostat-grown plants

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shen-Miller, J.; Dannenhoffer, J.; Hinchman, R.

1991-05-01

The clinostat is an apparatus that is used to mimic zero gravity in studies of plant growth in the absence of gravitropic response. Clinostat-grown tissue cultures of carrot exhibit significant increases both in the number of nuclei containing more than one nucleolus and in nucleolar volume. Oat seedlings germinated and grown on clinostats exhibit a decreased rate of shoot elongation, increased tissue sensitivity to applied auxin, and an increased response to gravitropic stimulation. Clinostat treatment clearly affects plant metabolism. The nucleolus is the region in the nucleus where ribosome synthesis and assembly take place. The 18S, 5.8S, and 25S ribosomalmore » genes, in tandem units, are located in the nucleolus. Ribosomes orchestrate the production of all proteins that are necessary for the maintenance of cell growth, development, and survival. A full study of the effects of nullification of gravitropism, by clinostat rotation, on nucleolar development in barley has been initiated. The authors study developmental changes of nucleolar number and diameter in clinostat-grown root tissues. Preliminary results show that barley roots exhibit changes in nucleolar number and diameter. Growth rates of barley root and shoot also appear to be reduced, in measurements of both length and weight.« less

High-affinity K+ uptake in pepper plants.

PubMed

Martínez-Cordero, M Angeles; Martínez, Vicente; Rubio, Francisco

2005-06-01

High-affinity K+ uptake is an essential process for plant nutrition under K+-limiting conditions. The results presented here demonstrate that pepper (Capsicum annuum) plants grown in the absence of NH4+ and starved of K+ show an NH4+-sensitive high-affinity K+ uptake that allows plant roots to deplete external K+ to values below 1 microM. When plants are grown in the presence of NH4+, high-affinity K+ uptake is not inhibited by NH4+. Although NH4+-grown plants deplete external K+ below 1 microM in the absence of NH4+, when 1 mM NH4+ is present they do not deplete external K+ below 10 microM. A K+ transporter of the HAK family, CaHAK1, is very likely mediating the NH4+-sensitive component of the high-affinity K+ uptake in pepper roots. CaHAK1 is strongly induced in the roots that show the NH4+-sensitive high-affinity K+ uptake and its induction is reduced in K+-starved plants grown in the presence of NH4+. The NH4+-insensitive K+ uptake may be mediated by an AKT1-like K+ channel.

Evidence that elevated CO2 levels can indirectly increase rhizosphere denitrifier activity

NASA Technical Reports Server (NTRS)

Smart, D. R.; Ritchie, K.; Stark, J. M.; Bugbee, B.

1997-01-01

We examined the influence of elevated CO2 concentration on denitrifier enzyme activity in wheat rhizoplanes by using controlled environments and solution culture techniques. Potential denitrification activity was from 3 to 24 times higher on roots that were grown under an elevated CO2 concentration of 1,000 micromoles of CO2 mol-1 than on roots grown under ambient levels of CO2. Nitrogen loss, as determined by a nitrogen mass balance, increased with elevated CO2 levels in the shoot environment and with a high NO3- concentration in the rooting zone. These results indicated that aerial CO2 concentration can play a role in rhizosphere denitrifier activity.

GRAVI-2 space experiment: investigating statoliths displacement and location effects on early stages of gravity perception pathways in lentil roots.

NASA Astrophysics Data System (ADS)

Bizet, François; Eche, Brigitte; Pereda Loth, Veronica; Badel, Eric; Legue, Valerie; Brunel, Nicole; Label, Philippe; Gérard, Joëlle

2016-07-01

The plants ability to orient their growth with respect to external stimuli such as gravity is a key factor for survival and acclimation to their environment. Belowground, plant roots modulate their growth towards gravity, allowing soil exploration and uptake of water and nutrients. In roots, gravity sensing cells called statocytes are located in the center of the root cap. Statocytes contain starch-filled plastids denser than the cytoplasm, which sedimentation along the direction of gravity is widely accepted as being involved into early stages of gravity perception (the starch-statolith hypothesis; Sack, 1991). Root gravitropism following statoliths displacement is based on auxin redistribution in the root apex, inducing differential growth between the root upward and downward sides. However at the cell scale, the chain of transduction starting from statoliths displacement and leading to auxin redistribution remains poorly documented. Signaling molecules such as calcium, reactive oxygen species, nitric oxide and inositol 1,4,5-triphosphate are serious candidates previously shown to be involved within minutes before modification of the expression of auxin-related genes (Morita, 2010; Sato et al., 2015). Here, we observe and quantify statoliths displacements and locations at various levels of gravity to investigate two hypothesis: (i) Are contacts between statoliths and the endoplasmic reticulum necessary to induce gravitropism? (ii) Are very low displacements of statoliths sufficient to initiate transduction pathways such as the calcium's one? These questionings have led to an experiment called GRAVI-2 which took place aboard the ISS in 2014. During the experiment, lentil roots were grown in the European modular cultivation system for several hours in microgravity and were then submitted to short high gravity stimulus (5 and 15 minutes at 2 g) before the return to Earth for analyses. Ongoing cytological measurements will reveal the effects of statoliths displacement and location on intracellular calcium localization. Complementary RNA sequencing was done and current transcriptomic analyses will show the regulation of calcium-downstream gene expression and of auxin dependent pathways at two short time steps following gravistimulus. In addition, some of the lentil roots grown in microgravity aboard the ISS were submitted for several hours to low level of gravity (10-2 g) close to the detection threshold determined on a previous experiment (GRAVI-1; Driss-Ecole et al., 2008). Root gravitropism in response to such a low level of gravity was investigated and compared to the very low statoliths displacement expected. This study give insights about the molecular mechanisms underlying the very high sensitivity of roots to gravity and are among the firsts studies involving global transcriptomic analyses of root material grown in microgravity. Keywords: Calcium; ISS; Microgravity; Root; Statholith; Transcriptomic Acknowledgments: The authors thank G. Perbal, D. Driss-Ecole, the European space agency and the Norwegian user support and operations center team for their considerable help in the preparation and achievement of the GRAVI experiments. This work should not have been possible without the financial supports of the Centre National d'Etudes Spatiales (CNES) through a postdoctoral fellowship. References: Driss-Ecole, D., Legué, V., Carnero-Diaz, E. and Perbal, G. 2008. Gravisensitivity and automorphogenesis of lentil seedling roots grown on board the International Space Station. Physiologia Plantarum. 134, 1 (2008), 191-201. Morita, M. 2010. Directional Gravity Sensing in Gravitropism. Plant Biology. 61, 1 (2010), 705-720. Sack, F.D. 1991. Plant gravity sensing. International review of cytology. 127, (1991), 193-252. Sato, E.M., Hijazi, H., Bennett, M.J., Vissenberg, K. and Swarup, R. 2015. New insights into root gravitropic signalling. Journal of experimental botany. 66, 8 (Apr. 2015), 2155-65.

Responses to iron limitation in Hordeum vulgare L. as affected by the atmospheric CO2 concentration.

PubMed

Haase, S; Rothe, A; Kania, A; Wasaki, J; Römheld, V; Engels, C; Kandeler, E; Neumann, G

2008-01-01

Elevated atmospheric CO2 treatments stimulated biomass production in Fe-sufficient and Fe-deficient barley plants, both in hydroponics and in soil culture. Root/shoot biomass ratio was increased in severely Fe-deficient plants grown in hydroponics but not under moderate Fe limitation in soil culture. Significantly increased biomass production in high CO2 treatments, even under severe Fe deficiency in hydroponic culture, indicates an improved internal Fe utilization. Iron deficiency-induced secretion of PS in 0.5 to 2.5 cm sub-apical root zones was increased by 74% in response to elevated CO2 treatments of barley plants in hydroponics but no PS were detectable in root exudates collected from soil-grown plants. This may be attributed to suppression of PS release by internal Fe concentrations above the critical level for Fe deficiency, determined at final harvest for soil-grown barley plants, even without additional Fe supply. However, extremely low concentrations of easily plant-available Fe in the investigated soil and low Fe seed reserves suggest a contribution of PS-mediated Fe mobilization from sparingly soluble Fe sources to Fe acquisition of the soil-grown barley plants during the preceding culture period. Higher Fe contents in shoots (+52%) of plants grown in soil culture without Fe supply under elevated atmospheric CO2 concentrations may indicate an increased efficiency for Fe acquisition. No significant influence on diversity and function of rhizosphere-bacterial communities was detectable in the outer rhizosphere soil (0-3 mm distance from the root surface) by DGGE of 16S rRNA gene fragments and analysis of marker enzyme activities for C-, N-, and P-cycles.

Slope Root biomechanical properties and their contribution to soil reinforcement in the Landslide-prone region, the Bailong River Basin

NASA Astrophysics Data System (ADS)

Wang, X.; Hong, M.; Huang, Z.; Zhao, Y.; Zhang, Y.

2016-12-01

The presence of vegetation increases soil burden stability along slopes and therefore reduces soil erosion. The contribution of the vegetation is due to the root's mechanical (reinforcing soil shear resistance) controls on superficial landslide. The study focused on the biotechnical characteristics of the root system of commonly grown shrub species in the Bailong River Basin, one of the most serious geo-hazards regions in China. The aim of this paper is to increase the understanding on slope root biomechanical properties of different shrubs species and their contribution to soil reinforcement. Field investigations were carried out to estimate the root density distribution with depth (root area ratio). Laboratory tests were conducted to measure the root tensile breaking force and the root tensile strength. Root tensile strength measurements were carried out on single root specimens and root area ratio was estimated analyzing the whole root system. The direct shear tests were used to quantify the soil mechanical reinforcement. The improvement of soil mechanical properties obtained by the presence of shrubs was estimated using two different models(the Fibrt Bundle Model and the Finite Element Model). The results indicates that the soil-root system shear strength of Robinia pseudoacacia Linn (L.), Populus simonii (L.), Olea europaea (L.), and Zanthoxylum bungeanum (L.) increment ranged from 62.4 to 26.3 kPa and its effect on the slope stability was significantly different. Robinia pseudoacacia Linn (L.) roots presented the highest tensile strength and soil reinforcement values. Similarly at each considered depth Robinia pseudoacacia Linn (L.) showed that the highest soil reinforcement effect (1461N) while Olea europaea (L.) presented the lowest soil reinforcement effect (1329N). The finite element model shows that the FoS of Zanthoxylum bungeanum (L.) is the largest of these plants when considering root additional cohesion. This research can provide a basic theory of afforestation mode in spatial distribution and hence control shallow landslide.

Effects of microgravity and clinorotation on stress ethylene production in two starchless mutants of Arabidopsis thaliana

NASA Technical Reports Server (NTRS)

Gallegos, Gregory L.; Hilaire, Emmanuel M.; Peterson, Barbara V.; Brown, Christopher S.; Guikema, James A.

1995-01-01

Starch filled plastids termed amyloplasts, contained within columella cells of the root caps of higher plant roots, are believed to play a statolith-like role in the gravitropic response of roots. Plants having amyloplasts containing less starch exhibit a corresponding reduction in gravitropic response. We have observed enhanced ethylene production by sweet clover (Melilotus alba L.) seedlings grown in the altered gravity condition of a slow rotating clinostat, and have suggested that this is a stress response resulting from continuous gravistimulation rather than as a result of the simulation of a microgravity condition. If so, we expect that plants deficient in starch accumulation in amyloplasts may produce less stress ethylene when grown on a clinostat. Therefore, we have grown Arabidopsis thaliana in the small, closed environment of the Fluid Processing Apparatus (FPA). In this preliminary report we compare stationary plants with clinorotated and those grown in microgravity aboard Discovery during the STS-63 flight in February 1995. In addition to wildtype, two mutants deficient in starch biosynthesis, mutants TC7 and TL25, which are, respectively, deficient in the activity of amyloplast phosphoglucomutase and ADP-glucose pyrophosphorylase, were grown for three days before being fixed within the FPA. Gas samples were aspirated from the growth chambers and carbon dioxide and ethylene concentations were measured using a gas chromatograph. The fixed tissue is currently undergoing further morphologic and microscopic characterization.

In Vitro Adhesion of Streptococcus sanguinis to Dentine Root Surface After Treatment with Er:Yag Laser, Ultrasonic System, or Manual Curette

PubMed Central

Martins, Fernanda L.; Giorgetti, Ana Paula O.; de Freitas, Patrícia M.; Duarte, Poliana M.

2009-01-01

Abstract Objective: The purpose of this in vitro study was to evaluate the dentine root surface roughness and the adherence of Streptococcus sanguinis (ATCC 10556) after treatment with an ultrasonic system, Er:YAG laser, or manual curette. Background Data: Bacterial adhesion and formation of dental biofilm after scaling and root planing may be a challenge to the long-term stability of periodontal therapy. Materials and Methods: Forty flattened bovine roots were randomly assigned to one of the following groups: ultrasonic system (n = 10); Er:YAG laser (n = 10); manual curette (n = 10); or control untreated roots (n = 10). The mean surface roughness (Ra, μm) of the specimens before and after exposure to each treatment was determined using a surface profilometer. In addition, S. sanguinis was grown on the treated and untreated specimens and the amounts of retained bacteria on the surfaces were measured by culture method. Results: All treatments increased the Ra; however, the roughest surface was produced by the curettes. In addition, the specimens treated with curettes showed the highest S. sanguinis adhesion. There was a significant positive correlation between roughness values and bacterial cells counts. Conclusion: S. sanguinis adhesion was the highest on the curette-treated dentine root surfaces, which also presented the greatest surface roughness. PMID:19712018

Transgenic barley (Hordeum vulgare L.) expressing the wheat aluminium resistance gene (TaALMT1) shows enhanced phosphorus nutrition and grain production when grown on an acid soil.

PubMed

Delhaize, Emmanuel; Taylor, Phillip; Hocking, Peter J; Simpson, Richard J; Ryan, Peter R; Richardson, Alan E

2009-06-01

Barley (Hordeum vulgare L.), genetically modified with the Al(3+) resistance gene of wheat (TaALMT1), was compared with a non-transformed sibling line when grown on an acidic and highly phosphate-fixing ferrosol supplied with a range of phosphorus concentrations. In short-term pot trials (26 days), transgenic barley expressing TaALMT1 (GP-ALMT1) was more efficient than a non-transformed sibling line (GP) at taking up phosphorus on acid soil, but the genotypes did not differ when the soil was limed. Differences in phosphorus uptake efficiency on acid soil could be attributed not only to the differential effects of aluminium toxicity on root growth between the genotypes, but also to differences in phosphorus uptake per unit root length. Although GP-ALMT1 out-performed GP on acid soil, it was still not as efficient at taking up phosphorus as plants grown on limed soil. GP-ALMT1 plants grown in acid soil possessed substantially smaller rhizosheaths than those grown in limed soil, suggesting that root hairs were shorter. This is a probable reason for the lower phosphorus uptake efficiency. When grown to maturity in large pots, GP-ALMT1 plants produced more than twice the grain as GP plants grown on acid soil and 80% of the grain produced by limed controls. Expression of TaALMT1 in barley was not associated with a penalty in either total shoot or grain production in the absence of Al(3+), with both genotypes showing equivalent yields in limed soil. These findings demonstrate that an important crop species can be genetically engineered to successfully increase grain production on an acid soil.

Gravitropism interferes with hydrotropism via counteracting auxin dynamics in cucumber roots: clinorotation and spaceflight experiments.

PubMed

Morohashi, Keita; Okamoto, Miki; Yamazaki, Chiaki; Fujii, Nobuharu; Miyazawa, Yutaka; Kamada, Motoshi; Kasahara, Haruo; Osada, Ikuko; Shimazu, Toru; Fusejima, Yasuo; Higashibata, Akira; Yamazaki, Takashi; Ishioka, Noriaki; Kobayashi, Akie; Takahashi, Hideyuki

2017-09-01

Roots of land plants show gravitropism and hydrotropism in response to gravity and moisture gradients, respectively, for controlling their growth orientation. Gravitropism interferes with hydrotropism, although the mechanistic aspects are poorly understood. Here, we differentiated hydrotropism from gravitropism in cucumber roots by conducting clinorotation and spaceflight experiments. We also compared mechanisms regulating hydrotropism and auxin-regulated gravitropism. Clinorotated or microgravity (μG)-grown cucumber seedling roots hydrotropically bent toward wet substrate in the presence of moisture gradients, but they grew straight in the direction of normal gravitational force at the Earth's surface (1G) on the ground or centrifuge-generated 1G in space. The roots appeared to become hydrotropically more sensitive to moisture gradients under μG conditions in space. Auxin transport inhibitors significantly reduced the hydrotropic response of clinorotated seedling roots. The auxin efflux protein CsPIN5 was differentially expressed in roots of both clinorotated and μG-grown seedlings; with higher expression in the high-humidity (concave) side than the low-humidity (convex) side of hydrotropically responding roots. Our results suggest that roots become hydrotropically sensitive in μG, and CsPIN5-mediated auxin transport has an important role in inducing root hydrotropism. Thus, hydrotropic and gravitropic responses in cucumber roots may compete via differential auxin dynamics established in response to moisture gradients and gravity. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

Involvement of hexokinase1 in plant growth promotion as mediated by Burkholderia phytofirmans.

PubMed

Park, Jae Min; Lazarovits, George

2014-06-01

Potato plantlets inoculated with strain PsJN of the bacterium Burkholderia phytofirmans exhibit consistent and significant increases in plant growth under in vitro conditions, when compared with uninoculated plants. The greatest influence on the degree and type of growth enhancement that develops has been shown to be mediated by the sugar concentration in the agar media. Bacterial growth promotion has been suggested in other studies to be regulated by the sugar sensor enzyme hexokinase1, the role of which is activation of glucose phosphorylation. In this present study, we examined the co-relationship between root and stem development in potato plants treated with PsJN and the activity of hexokinase1. Plants grown in the presence of 1.5% and 3% sucrose showed increased levels of hexokinase1 activity only in the roots of inoculated plants, suggesting that the increased enzyme levels may be associated with root growth. Analysis for mRNA using reverse transcriptase did not reveal any significant differences in transcription levels of the gene between inoculated and uninoculated plants. When PsJN-inoculated plants were grown in 1.5% and 3% concentrations of glucose and fructose, stem height and mass, leaf number, root mass, and overall biomass increased. No growth promotion occurred when PsJN-inoculated plants were grown in 3% maltose. Subsequently, a hexokinase1 activity assay showed that PsJN-induced growth of potato plants was found to only occur when plants were grown in the presence of sugars that are recognized by the plant hexokinase1. The results suggest that PsJN may enhance sugar uptake in plants by direct or indirect stimulation of hexokinase1 activity in roots and this results in enhanced overall plant growth.

Production of the Antibiotic Phenazine-1-Carboxylic Acid by Fluorescent Pseudomonas Species in the Rhizosphere of Wheat

PubMed Central

Thomashow, Linda S.; Weller, David M.; Bonsall, Robert F.; Pierson, Leland S.

1990-01-01

Pseudomonas fluorescens 2-79 and P. aureofaciens 30-84 produce the antibiotic phenazine-1-carboxylic acid and suppress take-all, an important root disease of wheat caused by Gaeumannomyces graminis var. tritici. To determine whether the antibiotic is produced in situ, wheat seeds were treated with strain 2-79 or 30-84 or with phenazine-nonproducing mutants or were left untreated and then were sown in natural or steamed soil in the field or growth chamber. The antibiotic was isolated only from roots of wheat colonized by strain 2-79 or 30-84 in both growth chamber and field studies. No antibiotic was recovered from the roots of seedlings grown from seeds treated with phenazine-nonproducing mutants or left untreated. In natural soils, comparable amounts of antibiotic (27 to 43 ng/g of root with adhering soil) were recovered from roots colonized by strain 2-79 whether or not the pathogen was present. Roots of plants grown in steamed soil yielded larger bacterial populations and more antibiotic than roots from natural soils. In steamed and natural soils, roots from which the antibiotic was recovered had significantly less disease than roots with no antibiotic, indicating that suppression of take-all is related directly to the presence of the antibiotic in the rhizosphere. PMID:16348176

Changes in root hydraulic conductivity facilitate the overall hydraulic response of rice (Oryza sativa L.) cultivars to salt and osmotic stress.

PubMed

Meng, Delong; Fricke, Wieland

2017-04-01

The aim of the present work was to assess the significance of changes in root AQP gene expression and hydraulic conductivity (Lp) in the regulation of water balance in two hydroponically-grown rice cultivars (Azucena, Bala) which differ in root morphology, stomatal regulation and aquaporin (AQP) isoform expression. Plants were exposed to NaCl (25 mM, 50 mM) and osmotic stress (5%, 10% PEG6000). Root Lp was determined for exuding root systems (osmotic forces driving water uptake; 'exudation Lp') and transpiring plants (hydrostatic forces dominating; 'transpiration-Lp'). Gene expression was analysed by qPCR. Stress treatments caused a consistent and significant decrease in plant growth, transpirational water loss, stomatal conductance, shoot-to-root surface area ratio and root Lp. Comparison of exudation-with transpiration-Lp supported a significant contribution of AQP-facilitated water flow to root water uptake. Changes in root Lp in response to treatments were correlated much stronger with root morphological characteristics, such as the number of main and lateral roots, surface area ratio of root to shoot and plant transpiration rate than with AQP gene expression. Changes in root Lp, involving AQP function, form an integral part of the plant hydraulic response to stress and facilitate changes in the root-to-shoot surface area ratio, transpiration and stomatal conductance. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Interactions between soil and tree roots accelerate long-term soil carbon decomposition.

PubMed

Dijkstra, Feike A; Cheng, Weixin

2007-11-01

Decomposition of soil organic carbon (SOC) is the main process governing the release of CO(2) into the atmosphere from terrestrial systems. Although the importance of soil-root interactions for SOC decomposition has increasingly been recognized, their long-term effect on SOC decomposition remains poorly understood. Here we provide experimental evidence for a rhizosphere priming effect, in which interactions between soil and tree roots substantially accelerate SOC decomposition. In a 395-day greenhouse study with Ponderosa pine and Fremont cottonwood trees grown in three different soils, SOC decomposition in the planted treatments was significantly greater (up to 225%) than in soil incubations alone. This rhizosphere priming effect persisted throughout the experiment, until well after initial soil disturbance, and increased with a greater amount of root-derived SOC formed during the experiment. Loss of old SOC was greater than the formation of new C, suggesting that increased C inputs from roots could result in net soil C loss.

7 CFR 319.77-2 - Regulated articles.

Code of Federal Regulations, 2010 CFR

2010-01-01

... from Canada only under the conditions described in § 319.77-4 of this subpart. (a) Trees without roots (e.g., Christmas trees), unless they were greenhouse-grown throughout the year; (b) Trees with roots...

Spatial and temporal patterns of root distribution in developing stands of four woody crop species grown with drip irrigation and fertilization

Treesearch

Mark Coleman

2007-01-01

In forest trees, roots mediate such significant carbon fluxes as primary production and soil C02 efflux. Despite the central role of roots in these critical processes, information on root distribution during stand establishment is limited, yet must be described to accurately predict how various forest types, which are growing with a range of...

Effect of aluminum treatment on proteomes of radicles of seeds derived from Al-treated tomato plants

USDA-ARS?s Scientific Manuscript database

Aluminum (Al) toxicity is a major constraint to plant growth and crop yield in acid soils. Tomato cultivars are especially susceptible to excessive A1 3+ accumulated in the root zone. In this study, tomato plants were grown in a hydroponic culture system supplemented with 50 uM AlK(SO4)2. Seeds harv...

Nitric Acid and Benomyl Stimulate Rapid Height Growth of Longleaf Pine

Treesearch

A.G. Kais; R.C. Hare; J.P. Barnett

1984-01-01

Rapid height growth of longleaf pine seedlings, important to production of uniform, even-aged stands, can be promoted by controlling brown-spot needle blight and weed competition, and by increasing soil fertility. Root systems of container-grown longleaf pine seedlings were dip-treated in either benomyl/clay mix (10 percent a.i. benomyl) or clay control and planted...

Performance of container-grown seedlings of American chestnut backcross hybrids BC3 F3 generation in central Louisiana

Treesearch

Shi-Jean Susana Sung; Stacy L. Clark; Scott Schlarbaum; Daniel C. Dey; Daniel J. Leduc

2016-01-01

Seedlings from two families of the BC3F3 backcross generation of the American chestnut (Castanea dentata) and Chinese chestnut (C. mollissima) were cultured in 2013 in Missouri using the Root Production Method®, a container-based system used to avoid disease problems associated with...

Douglas-fir container stock grown with fertilizer-amended media: Some preliminary results

Treesearch

Diane L. Haase; John Trobaugh; Robin Rose

2002-01-01

Incorporating fertilizer directly into the container growing media is a very new practice. Previously, it was believed that such a practice would result in toxicity due to direct contact with the root system and/or over fertilization. However, with the improved technology for controlled-release fertilizer, there is renewed interest in this practice. The objective of...

Effects of increasing root carbon investment on the mortality and resprouting of Haloxylon ammodendron seedlings under drought.

PubMed

Zhang, Y; Xie, J-B; Li, Y

2017-03-01

Tree mortality induced by drought is one of the most complex processes in ecology. Although two mechanisms associated with water and carbon balance are proposed to explain tree mortality, outstanding problems still exist. Here, in order to test how the root system benefits survival and resprouting of Haloxylon ammodendron seedlings, we examined the various water- and carbon-related physiological indicators (shoot water potential, photosynthesis, dark respiration, hydraulic conductance and non-structural carbohydrates [NSC]) of H. ammodendron seedlings, which were grown in drought and control conditions throughout a grow season in greenhouse. The survival time of the seedling root system (died 70 days after drought) doubled the survival time of the shoot (died at 35 days). Difference in survival time between shoot and root resulted from sustained root respiration supported by increased NSC in roots under drought. Furthermore, investment into the root contributed to resprouting following drought. Based on these results, a death criterion is proposed for this species. The time sequence of major events indicated that drought shifted carbon allocation between shoot and root and altered the flux among different sinks (growth, respiration or storage). The interaction of water and carbon processes determined death or survival of droughted H. ammodendron seedlings. These findings revealed that the 'root protection' strategy is critical in determining survival and resprouting of this species, and provided insights into the effects of carbon and water dynamics on tree mortality. © 2016 German Botanical Society and The Royal Botanical Society of the Netherlands.

Growth Enhancement and Developmental Modifications of in Vitro Grown Potato (Solanum tuberosum spp. tuberosum) as Affected by a Nonfluorescent Pseudomonas sp. 1

PubMed Central

Frommel, Marcos I.; Nowak, Jerzy; Lazarovits, George

1991-01-01

A plant growth-promoting rhizobacterium, designated Ps JN and isolated from onion roots, was identified as a nonfluorescent Pseudomonas sp. The percentage of similarity of Ps JN to P. gladioli (NCPPB 1891), P. cichorii (NCPPB 943), and P. viridiflava (NCPPB 635), as determined from 135 biochemical and physiological tests was 77, 70, and 66%, respectively. Ps JN persisted through successive generations of in vitro cultured potato plantlets, both as endophytic and epiphytic populations. In vitro inoculated potato (Solanum tuberosum) nodal explants produced plantlets with significant increases in root number (24-196%), root dry weight (44-201%), haulm dry weight (14-151%), and stem length (26-28%) as compared with noninoculated control plants. Bacterization also enhanced leaf hair formation (55-110%), secondary root branching, and total plant lignin content (43%). Other root colonizing bacteria or heat-killed cells of Ps JN had no significant effect on plant growth. Detached leaves from in vitro grown control plants, when exposed to 19°C and 50% relative humidity, lost 55% of their moisture content in 2.5 hours. Moisture loss by leaves of in vitro grown, bacterized plants, as well as greenhouse-acclimated, bacterized plants, and control plants, was less than 20%. Changes in stomatal closure appear to account for this difference. ImagesFigure 2Figure 4 PMID:16668277

Fungicides reduce Rhododendron root rot and mortality caused by Phytophthora cinnamomi, but not by P. plurivora

USDA-ARS?s Scientific Manuscript database

Rhododendron root rot, caused by several Phytophthora species, can cause devastating losses in nursery-grown plants. Most research on chemical control of root rot has focused on Phytophthora cinnamomi. However, it is unknown whether treatments recommended for P. cinnamomi are also effective for othe...

RoBuST: An Integrated Resource of Genomics Information for Plants in the Root and Bulb Crop Families Apiaceae and Alliaceae

USDA-ARS?s Scientific Manuscript database

Root and bulb vegetables (RBV) include carrots, celeriac (root celery), parsnips (Apiaceae), onions, garlic, and leek (Alliaceae) – food crops grown globally and consumed worldwide. Few data analysis platforms are currently available where data collection, annotation and integration initiatives are ...

7 CFR 301.86-5 - Issuance and cancellation of certificates and limited permits.

Code of Federal Regulations, 2011 CFR

2011-01-01

... plant. (3) Certification requirements for potatoes for consumption, root crops for consumption, garden... for consumption, root crops intended for consumption, garden or dry beans, or peas from the quarantined area only if the field in which the potatoes, root crops, garden or dry beans, or peas were grown...

7 CFR 301.86-5 - Issuance and cancellation of certificates and limited permits.

Code of Federal Regulations, 2014 CFR

2014-01-01

... plant. (3) Certification requirements for potatoes for consumption, root crops for consumption, garden... for consumption, root crops intended for consumption, garden or dry beans, or peas from the quarantined area only if the field in which the potatoes, root crops, garden or dry beans, or peas were grown...

7 CFR 301.86-5 - Issuance and cancellation of certificates and limited permits.

Code of Federal Regulations, 2012 CFR

2012-01-01

... plant. (3) Certification requirements for potatoes for consumption, root crops for consumption, garden... for consumption, root crops intended for consumption, garden or dry beans, or peas from the quarantined area only if the field in which the potatoes, root crops, garden or dry beans, or peas were grown...

Tillage and Water Deficit Stress Effects on Corn (Zea mays, L.) Root Distribution

USDA-ARS?s Scientific Manuscript database

One goal of soil management is to provide optimum conditions for root growth. Corn root distributions were measured in 2004 from a crop rotation – tillage experiment that was started in 2000. Corn was grown either following corn or following sunflower with either no till or deep chisel tillage. Wate...

Adult Education & Human Resource Development: Overlapping and Disparate Fields

ERIC Educational Resources Information Center

Watkins, Karen E.; Marsick, Victoria J.

2014-01-01

Adult education and human resource development as fields of practice and study share some roots in common but have grown in different directions in their histories. Adult education's roots focused initially on citizenship for a democratic society, whereas human resource development's roots are in performance at work. While they have…

Plasma membrane NADH oxidase of maize roots responds to gravity and imposed centrifugal forces

NASA Technical Reports Server (NTRS)

Bacon, E.; Morre, D. J.

2001-01-01

NADH oxidase activities measured with excised roots of dark-grown maize (Zea mays) seedlings and with isolated plasma membrane vesicles from roots of dark-grown maize oscillated with a regular period length of 24 min and were inhibited by the synthetic auxin 2,4-dichlorophenoxyacetic [correction of dichorophenoxyacetic] acid. The activities also responded to orientation with respect to gravity and to imposed centrifugal forces. Turning the roots upside down resulted in stimulation of the activity with a lag of about 10 min. Returning the sections to the normal upright position resulted in a return to initial rates. The activity was stimulated reversibly to a maximum of about 2-fold with isolated plasma membrane vesicles, when subjected to centrifugal forces of 25 to 250 x g for 1 to 4 min duration. These findings are the first report of a gravity-responsive enzymatic activity of plant roots inhibited by auxin and potentially related to the gravity-induced growth response. c2001 Editions scientifiques et medicales Elsevier SAS.

Exogenous Nitric Oxide (NO) Interferes with Lead (Pb)-Induced Toxicity by Detoxifying Reactive Oxygen Species in Hydroponically Grown Wheat (Triticum aestivum) Roots

PubMed Central

Kaur, Gurpreet; Singh, Harminder Pal; Batish, Daizy R.; Mahajan, Priyanka; Kohli, Ravinder Kumar; Rishi, Valbha

2015-01-01

Nitric Oxide (NO) is a bioactive signaling molecule that mediates a variety of biotic and abiotic stresses. The present study investigated the role of NO (as SNP [sodium nitroprusside]) in ameliorating lead (Pb)-toxicity in Triticum aestivum (wheat) roots. Pb (50 and 250 μM) alone and in combination with SNP (100 μM) was given to hydroponically grown wheat roots for a period of 0–8 h. NO supplementation reduced the accumulation of oxidative stress markers (malondialdehyde, conjugated dienes, hydroxyl ions and superoxide anion) and decreased the antioxidant enzyme activity in wheat roots particularly up to 6 h, thereby suggesting its role as an antioxidant. NO ameliorated Pb-induced membrane damage in wheat roots as evidenced by decreased ion-leakage and in situ histochemical localization. Pb-exposure significantly decreased in vivo NO level. The study concludes that exogenous NO partially ameliorates Pb-toxicity, but could not restore the plant growth on prolonged Pb-exposure. PMID:26402793

Production of the quinone-methide triterpene maytenin by in vitro adventitious roots of Peritassa campestris (Cambess.) A.C.Sm. (Celastraceae) and rapid detection and identification by APCI-IT-MS/MS.

PubMed

Paz, Tiago Antunes; dos Santos, Vânia A F F M; Inácio, Marielle Cascaes; Pina, Edieidia Souza; Pereira, Ana Maria Soares; Furlan, Maysa

2013-01-01

Establishment of adventitious root cultures of Peritassa campestris (Celastraceae) was achieved from seed cotyledons cultured in semisolid Woody Plant Medium (WPM) supplemented with 2% sucrose, 0.01% PVP, and 4.0 mg L⁻¹ IBA. Culture period on accumulation of biomass and quinone-methide triterpene maytenin in adventitious root were investigated. The accumulation of maytenin in these roots was compared with its accumulation in the roots of seedlings grown in a greenhouse (one year old). A rapid detection and identification of maytenin by direct injection into an atmospheric-pressure chemical ionization ion trap tandem mass spectrometer (APCI-IT-MS/MS) were performed without prior chromatographic separation. In vitro, the greatest accumulation of biomass occurred within 60 days of culture. The highest level of maytenin--972.11  μ g·g⁻¹ dry weight--was detected at seven days of cultivation; this value was 5.55-fold higher than that found in the roots of seedlings grown in a greenhouse.

Production of the Quinone-Methide Triterpene Maytenin by In Vitro Adventitious Roots of Peritassa campestris (Cambess.) A.C.Sm. (Celastraceae) and Rapid Detection and Identification by APCI-IT-MS/MS

PubMed Central

Paz, Tiago Antunes; dos Santos, Vânia A. F. F. M.; Inácio, Marielle Cascaes; Pina, Edieidia Souza; Pereira, Ana Maria Soares; Furlan, Maysa

2013-01-01

Establishment of adventitious root cultures of Peritassa campestris (Celastraceae) was achieved from seed cotyledons cultured in semisolid Woody Plant Medium (WPM) supplemented with 2% sucrose, 0.01% PVP, and 4.0 mg L−1 IBA. Culture period on accumulation of biomass and quinone-methide triterpene maytenin in adventitious root were investigated. The accumulation of maytenin in these roots was compared with its accumulation in the roots of seedlings grown in a greenhouse (one year old). A rapid detection and identification of maytenin by direct injection into an atmospheric-pressure chemical ionization ion trap tandem mass spectrometer (APCI-IT-MS/MS) were performed without prior chromatographic separation. In vitro, the greatest accumulation of biomass occurred within 60 days of culture. The highest level of maytenin—972.11 μg·g−1 dry weight—was detected at seven days of cultivation; this value was 5.55-fold higher than that found in the roots of seedlings grown in a greenhouse. PMID:24205504

Formin homology 1 (OsFH1) regulates root-hair elongation in rice (Oryza sativa).

PubMed

Huang, Jin; Kim, Chul Min; Xuan, Yuan-hu; Liu, Jingmiao; Kim, Tae Ho; Kim, Bo-Kyeong; Han, Chang-deok

2013-05-01

The outgrowth of root hairs from the epidermal cell layer is regulated by a strict genetic regulatory system and external growth conditions. Rice plants cultivated in water-logged paddy land are exposed to a soil ecology that differs from the environment surrounding upland plants, such as Arabidopsis and maize. To identify genes that play important roles in root-hair growth, a forward genetics approach was used to screen for short-root-hair mutants. A short-root-hair mutant was identified, and the gene was isolated using map-based cloning and sequencing. The mutant harbored a point mutation at a splicing acceptor site, which led to truncation of OsFH1 (rice formin homology 1). Subsequent analysis of two additional T-DNA mutants verified that OsFH1 is important for root-hair elongation. Further studies revealed that the action of OsFH1 on root-hair growth is dependent on growth conditions. The mutant Osfh1 exhibited root-hair defects when roots were grown submerged in solution, and mutant roots produced normal root hairs in the air. However, root-hair phenotypes of mutants were not influenced by the external supply of hormones or carbohydrates, a deficiency of nutrients, such as Fe or P i , or aeration. This study shows that OsFH1 plays a significant role in root-hair elongation in a growth condition-dependent manner.

In situ and in vitro colonization of Cathaya argyrophylla (Pinaceae) by ectomycorrhizal fungi.

PubMed

Vaario, Lu-Min; Xing, Shu-Tang; Xie, Zong-Qiang; Lun, Zhi-Ming; Sun, Xue; Li, Yu Hua

2006-03-01

Cathaya argyrophylla, a critically endangered conifer, is found to grow at four isolated areas located in subtropical mountains of China. To examine the involvement and usefulness of mycorrhizas for sustaining the population of this tree, we compared the root system, morphology, and structure of mycorrhizal roots of C. argyrophylla, which were collected from a natural stand and an artificial stand, each grown at a different location. More mycorrhizal roots were found for trees from an artificial stand. The presence of extramatrical mycelium, mantle, and Hartig net revealed that C. argyrophylla formed an ectomycorrhizal association in both sampling sites. Starch granules were found in mycorrhizal roots collected only from a natural stand. The aseptic synthesis of C. argyrophylla and Cenococcum geophilum was established for the first time in vitro. Typical ectomycorrhizas formed on seedlings on RM medium containing 0.1 g/l glucose, 5 weeks after inoculation. By light microscopy, the synthesized mycorrhizas showed a thin mantle from which emanated extramatrical hyphae and highly branched Hartig net. A simple, rapid, and convenient mycorrhiza synthesis system was developed, which facilitates further studies on ectomycorrhizal development of C. argyrophylla.

Cell-Specific Production and Antimicrobial Activity of Naphthoquinones in Roots of Lithospermum erythrorhizon1

PubMed Central

Brigham, Lindy A.; Michaels, Paula J.; Flores, Hector E.

1999-01-01

Pigmented naphthoquinone derivatives of shikonin are produced at specific times and in specific cells of Lithospermum erythrorhizon roots. Normal pigment development is limited to root hairs and root border cells in hairy roots grown on “noninducing” medium, whereas induction of additional pigment production by abiotic (CuSO4) or biotic (fungal elicitor) factors increases the amount of total pigment, changes the ratios of derivatives produced, and initiates production of pigment de novo in epidermal cells. When the biological activity of these compounds was tested against soil-borne bacteria and fungi, a wide range of sensitivity was recorded. Acetyl-shikonin and β-hydroxyisovaleryl-shikonin, the two most abundant derivatives in both Agrobacterium rhizogenes-transformed “hairy-root” cultures and greenhouse-grown plant roots, were the most biologically active of the seven compounds tested. Hyphae of the pathogenic fungi Rhizoctonia solani, Pythium aphanidermatum, and Nectria hematococca induced localized pigment production upon contact with the roots. Challenge by R. solani crude elicitor increased shikonin derivative production 30-fold. We have studied the regulation of this suite of related, differentially produced, differentially active compounds to understand their role(s) in plant defense at the cellular level in the rhizosphere. PMID:9952436

Benzo[a]pyrene co-metabolism in the presence of plant root extracts and exudates: Implications for phytoremediation.

PubMed

Rentz, Jeremy A; Alvarez, Pedro J J; Schnoor, Jerald L

2005-08-01

Benzo[a]pyrene, a high molecular weight (HMW) polycyclic aromatic hydrocarbon (PAH) was removed from solution by Sphingomonas yanoikuyae JAR02 while growing on root products as a primary carbon and energy source. Plant root extracts of osage orange (Maclura pomifera), hybrid willow (Salix albaxmatsudana), or kou (Cordia subcordata), or plant root exudates of white mulberry (Morus alba) supported 15-20% benzo[a]pyrene removal over 24 h that was similar to a succinate grown culture and an unfed acetonitrile control. No differences were observed between the different root products tested. Mineralization of (14)C-7-benzo[a]pyrene by S. yanoikuyae JAR02 yielded 0.2 to 0.3% (14)CO(2) when grown with plant root products. Collectively, these observations were consistent with field observations of enhanced phytoremediation of HMW PAH and corroborated the hypothesis that co-metabolism may be a plant/microbe interaction important to rhizoremediation. However, degradation and mineralization was much less for root product-exposed cultures than salicylate-induced cultures, and suggested the rhizosphere may not be an optimal environment for HMW PAH degradation by Sphingomonas yanoikuyae JAR02.

Effect of silicon on wheat seedlings (Triticum turgidum L.) grown in hydroponics and exposed to 0 to 30 µM Cu.

PubMed

Keller, C; Rizwan, M; Davidian, J-C; Pokrovsky, O S; Bovet, N; Chaurand, P; Meunier, J-D

2015-04-01

Aqueous Si limits Cu uptake by a Si-accumulating plant via physicochemical mechanisms occurring at the root level. Sufficient Si supply may alleviate Cu toxicity in Cu-contaminated soils. Little information is available on the role of silicon (Si) in copper (Cu) tolerance while Cu toxicity is widespread in crops grown on Cu-contaminated soils. A hydroponic study was set up to investigate the influence of Si on Cu tolerance in durum wheat (Triticum turgidum L.) grown in 0, 0.7, 7.0 and 30 µM Cu without and with 1.0 mM Si, and to identify the mechanisms involved in mitigation of Cu toxicity. Si supply alleviated Cu toxicity in durum wheat at 30 µM Cu, while Cu significantly increased Si concentration in roots. Root length, photosynthetic pigments concentrations, macroelements, and organic anions (malate, acetate and aconitate) in roots, were also increased. Desorption experiments, XPS analysis of the outer thin root surface (≤100 Å) and µXRF analyses showed that Si increased adsorption of Cu at the root surface as well as Cu accumulation in the epidermis while Cu was localised in the central cylinder when Si was not applied. Copper was not detected in phytoliths. This study provides evidences for Si-mediated alleviation of Cu toxicity in durum wheat. It also shows that Si supplementation to plants exposed to increasing levels of Cu in solution induces non-simultaneous changes in physiological parameters. We propose a three-step mechanism occurring mainly at the root level and limiting Cu uptake and translocation to shoots: (i) increased Cu adsorption onto the outer thin layer root surface and immobilisation in the vicinity of root epidermis, (ii) increased Cu complexation by both inorganic and organic anions such as aconitate and, (iii) limitation of translocation through an enhanced thickening of a Si-loaded endodermis.

Characterization of low phosphorus insensitive Mutants Reveals a Crosstalk between Low Phosphorus-Induced Determinate Root Development and the Activation of Genes Involved in the Adaptation of Arabidopsis to Phosphorus Deficiency1

PubMed Central

Sánchez-Calderón, Lenin; López-Bucio, José; Chacón-López, Alejandra; Gutiérrez-Ortega, Abel; Hernández-Abreu, Esmeralda; Herrera-Estrella, Luis

2006-01-01

Low phosphorus (P) availability is one of the most limiting factors for plant productivity in many natural and agricultural ecosystems. Plants display a wide range of adaptive responses to cope with low P stress, which generally serve to enhance P availability in the soil and to increase its uptake by roots. In Arabidopsis (Arabidopsis thaliana), primary root growth inhibition and increased lateral root formation have been reported to occur in response to P limitation. To gain knowledge of the genetic mechanisms that regulate root architectural responses to P availability, we designed a screen for identifying Arabidopsis mutants that fail to arrest primary root growth when grown under low P conditions. Eleven low phosphorus insensitive (lpi) mutants that define at least four different complementation groups involved in primary root growth responses to P availability were identified. The lpi mutants do not show the typical determinate developmental program induced by P stress in the primary root. Other root developmental aspects of the low P rescue system, including increased root hair elongation and anthocyanin accumulation, remained unaltered in lpi mutants. In addition to the insensitivity of primary root growth inhibition, when subjected to P deprivation, lpi mutants show a reduced induction in the expression of several genes involved in the P starvation rescue system (PHOSPHATE TRANSPORTER 1 and 2, PURPLE ACID PHOSPHATASE 1, ACID PHOSPHATASE 5, and INDUCED BY PHOSPHATE STARVATION 1). Our results provide genetic support for the role of P as an important signal for postembryonic root development and root meristem maintenance and show a crosstalk in developmental and biochemical responses to P deprivation. PMID:16443695

Using mini-rockwool blocks as growing media for limited-cluster tomato production

NASA Technical Reports Server (NTRS)

Logendra, L. S.; Gianfagna, T. J.; Janes, H. W.

2001-01-01

Rockwool is an excellent growing medium for the hydroponic production of tomato; however, the standard size rockwool blocks [4 x 4 x 2.5 inches (10 x 10 x 6.3 cm) or 3 x 3 x 2.5 inches (7.5 x 7.5 x 6.3 cm)] are expensive. The following experiments were conducted with less expensive minirock wool blocks (MRBs), on rayon polyester material (RPM) as a bench top liner, to reduce the production cost of tomatoes (Lycopersicon esculentum) grown in a limited-cluster, ebb and flood hydroponic cultivation system. Fruit yield for single-cluster plants growing in MRBs [2 x 2 x 1.6 inches (5 x 5 x 4 cm) and 1.6 x 1.6 x 1.6 inches (4 x 4 x 4 cm)] was not significantly different from plants grown in larger sized blocks (3 x 3 x 2.5 inches). When the bench top was lined with RPM, roots penetrated the RPM, and an extensive root mat developed between the RPM and the bench top. The fruit yield from plants on RPM was significantly increased compared to plants without RPM due to increases in fruit size and fruit number. RPM also significantly reduced the incidence of blossom-end rot. In a second experiment, single- and double-cluster plants were grown on RPM. Fruit yield for double-cluster plants was 40% greater than for single-cluster plants due to an increase in fruit number, although the fruit were smaller in size. As in the first experiment, fruit yield for all plants grown in MRBs was not significantly different from plants grown in the larger sized blocks. MRBs and a RPM bench liner are an effective combination in the production of limited-cluster hydroponic tomatoes.

Rooting depth and root depth distribution of Trifolium repens × T. uniflorum interspecific hybrids.

PubMed

Nichols, S N; Hofmann, R W; Williams, W M; van Koten, C

2016-05-20

Traits related to root depth distribution were examined in Trifolium repens × T. uniflorum backcross 1 (BC 1 ) hybrids to determine whether root characteristics of white clover could be improved by interspecific hybridization. Two white clover cultivars, two T. uniflorum accessions and two BC 1 populations were grown in 1 -m deep tubes of sand culture. Maximum rooting depth and root mass distribution were measured at four harvests over time, and root distribution data were fitted with a regression model to provide measures of root system shape. Morphological traits were measured at two depths at harvest 3. Root system shape of the hybrids was more similar to T. uniflorum than to white clover. The hybrids and T. uniflorum had a higher rate of decrease in root mass with depth than white clover, which would result in higher proportions of root mass in the upper profile. Percentage total root mass at 100-200 mm depth was higher for T. uniflorum than white clover, and for Crusader BC 1 than 'Crusader'. Roots of the hybrids and T. uniflorum also penetrated deeper than those of white clover. T. uniflorum had thicker roots at 50-100 mm deep than the other entries, and more of its fine root mass at 400-500 mm. The hybrids and white clover had more of their fine root mass higher in the profile. Consequently, T. uniflorum had a higher root length density at 400-500 mm than most entries, and a smaller decrease in root length density with depth. These results demonstrate that rooting characteristics of white clover can be altered by hybridization with T. uniflorum, potentially improving water and nutrient acquisition and drought resistance. Root traits of T. uniflorum are likely to be adaptations to soil moisture and fertility in its natural environment. © The Author 2016. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Rooting depth and root depth distribution of Trifolium repens × T. uniflorum interspecific hybrids

PubMed Central

Nichols, S. N.; Hofmann, R. W.; Williams, W. M.; van Koten, C.

2016-01-01

Background and aims Traits related to root depth distribution were examined in Trifolium repens × T. uniflorum backcross 1 (BC1) hybrids to determine whether root characteristics of white clover could be improved by interspecific hybridization. Methods Two white clover cultivars, two T. uniflorum accessions and two BC1 populations were grown in 1 -m deep tubes of sand culture. Maximum rooting depth and root mass distribution were measured at four harvests over time, and root distribution data were fitted with a regression model to provide measures of root system shape. Morphological traits were measured at two depths at harvest 3. Key Results Root system shape of the hybrids was more similar to T. uniflorum than to white clover. The hybrids and T. uniflorum had a higher rate of decrease in root mass with depth than white clover, which would result in higher proportions of root mass in the upper profile. Percentage total root mass at 100–200 mm depth was higher for T. uniflorum than white clover, and for Crusader BC1 than ‘Crusader’. Roots of the hybrids and T. uniflorum also penetrated deeper than those of white clover. T. uniflorum had thicker roots at 50–100 mm deep than the other entries, and more of its fine root mass at 400–500 mm. The hybrids and white clover had more of their fine root mass higher in the profile. Consequently, T. uniflorum had a higher root length density at 400–500 mm than most entries, and a smaller decrease in root length density with depth. Conclusions These results demonstrate that rooting characteristics of white clover can be altered by hybridization with T. uniflorum, potentially improving water and nutrient acquisition and drought resistance. Root traits of T. uniflorum are likely to be adaptations to soil moisture and fertility in its natural environment. PMID:27208735

Developmental patterns of jicama (Pachyrhizus erosus (L.) Urban) plant and the chemical constituents of roots grown in Sonora, Mexico.

PubMed

Fernandez, M V; Warid, W A; Loaiza, J M; Montiel, A

1997-01-01

The developmental pattern of jicama (Pachyrhizus erosus (L.) Urban) was studied by sampling plants aged 20 to 36 weeks at weekly intervals. There was an increase in all characteristics of foliage: fresh and dry weight, number of leaves per plant, main stem length, number of leaves, nodes and internodes of the main stem; and in all root characteristics: fresh and dry weight, diameter and length. The chemical analysis was determined for roots at different plant ages. The range values for dry matter were 16.19-22.28%, protein 1.11-1.62%, fat 0.553-0.867%, crude fiber 0.3048-0.3943%, and ash 0.669-1.089%. The chemical constituents fluctuated with age but without specific trends. These values are considered the first record of roots produced by plants grown in Mexico.

Uptake of polybrominated diphenyl ethers by carrot and lettuce crops grown in compost-amended soils.

PubMed

Bizkarguenaga, E; Iparraguirre, A; Oliva, E; Quintana, J B; Rodil, R; Fernández, L A; Zuloaga, O; Prieto, A

2016-02-01

The uptake of polybrominated diphenyl ethers (PBDEs) by carrot and lettuce was investigated. Degradation of PBDEs in soil in the absence of the plants was discarded. Different carrot (Nantesa and Chantenay) and lettuce (Batavia Golden Spring and Summer Queen) varieties were grown in fortified or contaminated compost-amended soil mixtures under greenhouse conditions. After plant harvesting, roots (core and peel) and leaves were analyzed separately for carrot, while for lettuce, leaves and hearts were analyzed together. The corresponding bioconcentration factors (BCFs) were calculated. In carrots, a concentration gradient of 2,2',3,4,4',5'-hexabromodiphenyl ether (BDE-138) became evident that decreased from the root peel via root core to the leaves. For decabromodiphenyl ether (BDE-209) at the low concentration level (7 and 20 ng g(-1)), the leaves incorporated the highest concentration of the target substance. For lettuce, a decrease in the BCF value (from 0.24 to 0.02) was observed the higher the octanol-water partition coefficient, except in the case of BDE-183 (BCF = 0.51) and BDE-209 (BCF values from 0.41 to 0.74). Significant influence of the soils and crop varieties on the uptake could not be supported. Metabolic debromination, hydroxylation or methylation of the target PBDEs in the soil-plant system was not observed.

Nitrate concentration effects on NO3-N uptake and reduction, growth, and fruit yield in strawberry

NASA Technical Reports Server (NTRS)

Darnell, R. L.; Stutte, G. W.; Sager, J. C. (Principal Investigator)

2001-01-01

Strawberries (Fragaria xananassa Duch. 'Osogrande') were grown hydroponically with three NO3-N concentrations (3.75, 7.5, or 15.0 mM) to determine effects of varying concentration on NO3-N uptake and reduction rates, and to relate these processes to growth and fruit yield. Plants were grown for 32 weeks, and NO3-N uptake and nitrate reductase (NR) activities in roots and shoots were measured during vegetative and reproductive growth. In general, NO3-N uptake rates increased as NO3-N concentration in the hydroponics system increased. Tissue NO3- concentration also increased as external NO3-N concentration increased, reflecting the differences in uptake rates. There was no effect of external NO3-N concentration on NR activities in leaves or roots during either stage of development. Leaf NR activity averaged approximately 360 nmol NO2 formed/g fresh weight (FW)/h over both developmental stages, while NR activity in roots was much lower, averaging approximately 115 nmol NO2 formed/g FW/h. Vegetative organ FW, dry weight (DW), and total fruit yield were unaffected by NO3-N concentration. These data suggest that the inability of strawberry to increase growth and fruit yield in response to increasing NO3-N concentrations is not due to limitations in NO3-N uptake rates, but rather to limitations in NO3- reduction and/or assimilation in both roots and leaves.

Genome-Wide Small RNA Analysis of Soybean Reveals Auxin-Responsive microRNAs that are Differentially Expressed in Response to Salt Stress in Root Apex

PubMed Central

Sun, Zhengxi; Wang, Youning; Mou, Fupeng; Tian, Yinping; Chen, Liang; Zhang, Senlei; Jiang, Qiong; Li, Xia

2016-01-01

Root growth and the architecture of the root system in Arabidopsis are largely determined by root meristematic activity. Legume roots show strong developmental plasticity in response to both abiotic and biotic stimuli, including symbiotic rhizobia. However, a global analysis of gene regulation in the root meristem of soybean plants is lacking. In this study, we performed a global analysis of the small RNA transcriptome of root tips from soybean seedlings grown under normal and salt stress conditions. In total, 71 miRNA candidates, including known and novel variants of 59 miRNA families, were identified. We found 66 salt-responsive miRNAs in the soybean root meristem; among them, 22 are novel miRNAs. Interestingly, we found auxin-responsive cis-elements in the promoters of many salt-responsive miRNAs, implying that these miRNAs may be regulated by auxin and auxin signaling plays a key role in regulating the plasticity of the miRNAome and root development in soybean. A functional analysis of miR399, a salt-responsive miRNA in the root meristem, indicates the crucial role of this miRNA in modulating soybean root developmental plasticity. Our data provide novel insight into the miRNAome-mediated regulatory mechanism in soybean root growth under salt stress. PMID:26834773

Early root cap development and graviresponse in white clover (Trifolium repens) grown in space and on a two-axis clinostat

NASA Technical Reports Server (NTRS)

Smith, J. D.; Staehelin, L. A.; Todd, P.

1999-01-01

White clover (Trifolium repens) was germinated and grown in microgravity aboard the Space Shuttle (STS-60, 1994; STS-63, 1995), on Earth in stationary racks and in a slow-rotating two-axis clinostat. The objective of this study was to determine if normal root cap development and early plant gravity responses were dependent on gravitational cues. Seedlings were germinated in space and chemically fixed in orbit after 21, 40, and 72 h. Seedlings 96 h old were returned viable to earth. Germination and total seedling length were not dependent on gravity treatment. In space-flown seedlings, the number of cell stories in the root cap and the geometry of central columella cells did not differ from those of the Earth-grown seedlings. The root cap structure of clinorotated plants appeared similar to that of seedlings from microgravity, with the exception of three-day rotated plants, which displayed significant cellular damage in the columella region. Nuclear polarity did not depend on gravity; however, the positions of amyloplasts in the central columella cells were dependent on both the gravity treatment and the age of the seedlings. Seedlings from space, returned viable to earth, responded to horizontal stimulation as did 1 g controls, but seedlings rotated on the clinostat for the same duration had a reduced curvature response. This study demonstrates that initial root cap development is insensitive to either chronic clinorotation or microgravity. Soon after differentiation, however, clinorotation leads to loss of normal root cap structure and plant graviresponse while microgravity does not.

Metaproteomic identification of diazotrophic methanotrophs and their localization in root tissues of field-grown rice plants.

PubMed

Bao, Zhihua; Okubo, Takashi; Kubota, Kengo; Kasahara, Yasuhiro; Tsurumaru, Hirohito; Anda, Mizue; Ikeda, Seishi; Minamisawa, Kiwamu

2014-08-01

In a previous study by our group, CH4 oxidation and N2 fixation were simultaneously activated in the roots of wild-type rice plants in a paddy field with no N input; both processes are likely controlled by a rice gene for microbial symbiosis. The present study examined which microorganisms in rice roots were responsible for CH4 oxidation and N2 fixation under the field conditions. Metaproteomic analysis of root-associated bacteria from field-grown rice (Oryza sativa Nipponbare) revealed that nitrogenase complex-containing nitrogenase reductase (NifH) and the alpha subunit (NifD) and beta subunit (NifK) of dinitrogenase were mainly derived from type II methanotrophic bacteria of the family Methylocystaceae, including Methylosinus spp. Minor nitrogenase proteins such as Methylocella, Bradyrhizobium, Rhodopseudomonas, and Anaeromyxobacter were also detected. Methane monooxygenase proteins (PmoCBA and MmoXYZCBG) were detected in the same bacterial group of the Methylocystaceae. Because these results indicated that Methylocystaceae members mediate both CH4 oxidation and N2 fixation, we examined their localization in rice tissues by using catalyzed reporter deposition-fluorescence in situ hybridization (CARD-FISH). The methanotrophs were localized around the epidermal cells and vascular cylinder in the root tissues of the field-grown rice plants. Our metaproteomics and CARD-FISH results suggest that CH4 oxidation and N2 fixation are performed mainly by type II methanotrophs of the Methylocystaceae, including Methylosinus spp., inhabiting the vascular bundles and epidermal cells of rice roots. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

Acclimation of the crucifer Eutrema salsugineum to phosphate limitation is associated with constitutively high expression of phosphate-starvation genes.

PubMed

Velasco, Vera Marjorie Elauria; Mansbridge, John; Bremner, Samantha; Carruthers, Kimberley; Summers, Peter S; Sung, Wilson W L; Champigny, Marc J; Weretilnyk, Elizabeth A

2016-08-01

Eutrema salsugineum, a halophytic relative of Arabidopsis thaliana, was subjected to varying phosphate (Pi) treatments. Arabidopsis seedlings grown on 0.05 mm Pi displayed shortened primary roots, higher lateral root density and reduced shoot biomass allocation relative to those on 0.5 mm Pi, whereas Eutrema seedlings showed no difference in lateral root density and shoot biomass allocation. While a low Fe concentration mitigated the Pi deficiency response for Arabidopsis, Eutrema root architecture was unaltered, but adding NaCl increased Eutrema lateral root density almost 2-fold. Eutrema and Arabidopsis plants grown on soil without added Pi for 4 weeks had low shoot and root Pi content. Pi-deprived, soil-grown Arabidopsis plants were stunted with senescing older leaves, whereas Eutrema plants were visually indistinguishable from 2.5 mm Pi-supplemented plants. Genes associated with Pi starvation were analysed by RT-qPCR. EsIPS2, EsPHT1;4 and EsPAP17 showed up-regulated expression in Pi-deprived Eutrema plants, while EsPHR1, EsWRKY75 and EsRNS1 showed no induction. Absolute quantification of transcripts indicated that PHR1, WRKY75 and RNS1 were expressed at higher levels in Eutrema plants relative to those in Arabidopsis regardless of external Pi. The low phenotypic plasticity Eutrema displays to Pi supply is consistent with adaptation to chronic Pi deprivation in its extreme natural habitat. © 2016 The Authors. Plant, Cell & Environment published by John Wiley & Sons Ltd.

Root Zone Respiration on Hydroponically Grown Wheat Plant Systems

NASA Technical Reports Server (NTRS)

Soler-Crespo, R. A.; Monje, O. A.

2010-01-01

Root respiration is a biological phenomenon that controls plant growth and physiological development during a plant's lifespan. This process is dependent on the availability of oxygen in the system where the plant is located. In hydroponic systems, where plants are submerged in a solution containing vital nutrients but no type of soil, the availability of oxygen arises from the dissolved oxygen concentration in the solution. This oxygen concentration is dependent on the , gas-liquid interface formed on the upper surface of the liquid, as given by Henry's Law, depending on pressure and temperature conditions. Respiration rates of the plants rise as biomass and root zone increase with age. The respiration rate of Apogee wheat plants (Triticum aestivum) was measured as a function of light intensity (catalytic for photosynthesis) and CO2 concentration to determine their effect on respiration rates. To determine their effects on respiration rate and plant growth microbial communities were introduced into the system, by Innoculum. Surfactants were introduced, simulating gray-water usage in space, as another factor to determine their effect on chemical oxygen demand of microbials and on respiration rates of the plants. It is expected to see small effects from changes in CO2 concentration or light levels, and to see root respiration decrease in an exponential manner with plant age and microbial activity.

Root biomass, turnover and net primary productivity of a coffee agroforestry system in Costa Rica: effects of soil depth, shade trees, distance to row and coffee age

PubMed Central

Defrenet, Elsa; Roupsard, Olivier; Van den Meersche, Karel; Charbonnier, Fabien; Pastor Pérez-Molina, Junior; Khac, Emmanuelle; Prieto, Iván; Stokes, Alexia; Roumet, Catherine; Rapidel, Bruno; de Melo Virginio Filho, Elias; Vargas, Victor J.; Robelo, Diego; Barquero, Alejandra; Jourdan, Christophe

2016-01-01

Background and Aims In Costa Rica, coffee (Coffea arabica) plants are often grown in agroforests. However, it is not known if shade-inducing trees reduce coffee plant biomass through root competition, and hence alter overall net primary productivity (NPP). We estimated biomass and NPP at the stand level, taking into account deep roots and the position of plants with regard to trees. Methods Stem growth and root biomass, turnover and decomposition were measured in mixed coffee/tree (Erythrina poeppigiana) plantations. Growth ring width and number at the stem base were estimated along with stem basal area on a range of plant sizes. Root biomass and fine root density were measured in trenches to a depth of 4 m. To take into account the below-ground heterogeneity of the agroforestry system, fine root turnover was measured by sequential soil coring (to a depth of 30 cm) over 1 year and at different locations (in full sun or under trees and in rows/inter-rows). Allometric relationships were used to calculate NPP of perennial components, which was then scaled up to the stand level. Key Results Annual ring width at the stem base increased up to 2·5 mm yr−1 with plant age (over a 44-year period). Nearly all (92 %) coffee root biomass was located in the top 1·5 m, and only 8 % from 1·5 m to a depth of 4 m. Perennial woody root biomass was 16 t ha−1 and NPP of perennial roots was 1·3 t ha−1 yr−1. Fine root biomass (0–30 cm) was two-fold higher in the row compared with between rows. Fine root biomass was 2·29 t ha−1 (12 % of total root biomass) and NPP of fine roots was 2·96 t ha−1 yr−1 (69 % of total root NPP). Fine root turnover was 1·3 yr−1 and lifespan was 0·8 years. Conclusions Coffee root systems comprised 49 % of the total plant biomass; such a high ratio is possibly a consequence of shoot pruning. There was no significant effect of trees on coffee fine root biomass, suggesting that coffee root systems are very competitive in the topsoil. PMID:27551026

Comparing Planting Tools for Container Longleaf Pine

Treesearch

Daniel J. Leduc; James D. Haywood; Shi-Jean Susana Sung

2011-01-01

We examined if compressing the soil to make a planting hole with a custom-built, solid round dibble versus coring the soil with a commercially available tube dibble influenced container-grown longleaf pine seedling development differently. Seven teen months after planting, the planting tool did not significantly affect root collar diameter, shoot or root mass, root-to-...

The Allium Test--A Simple, Eukaryote Genotoxicity Assay.

ERIC Educational Resources Information Center

Babich, H.; Segall, M. A.; Fox, K. D.

1997-01-01

Explains the allium test in which roots are excised from onion bulblets grown in aqueous solutions of a test agent. Root tips are then isolated and stained with aceto-orcein, and chromosomal aberrations are microscopically observed. (Author/AIM)

Membrane proteins involved in transport, vesicle traffic and Ca(2+) signaling increase in beetroots grown in saline soils.

PubMed

Lino, Bárbara; Chagolla, Alicia; E González de la Vara, Luis

2016-07-01

By separating plasma membrane proteins according to their hydropathy from beetroots grown in saline soils, several proteins probably involved in salt tolerance were identified by mass spectrometry. Beetroots, as a salt-tolerant crop, have developed mechanisms to cope with stresses associated with saline soils. To observe which plasma membrane (PM) proteins were more abundant in beet roots grown in saline soils, beet root plants were irrigated with water or 0.2 M NaCl. PM-enriched membrane preparations were obtained from these plants, and their proteins were separated according to their hydropathy by serial phase partitioning with Triton X-114. Some proteins whose abundance increased visibly in membranes from salt-grown beetroots were identified by mass spectrometry. Among them, there was a V-type H(+)-ATPase (probably from contaminating vacuolar membranes), which increased with salt at all stages of beetroots' development. Proteins involved in solute transport (an H(+)-transporting PPase and annexins), vesicle traffic (clathrin and synaptotagmins), signal perception and transduction (protein kinases and phospholipases, mostly involved in calcium signaling) and metabolism, appeared to increase in salt-grown beetroot PM-enriched membranes. These results suggest that PM and vacuolar proteins involved in transport, metabolism and signal transduction increase in beet roots adapted to saline soils. In addition, these results show that serial phase partitioning with Triton X-114 is a useful method to separate membrane proteins for their identification by mass spectrometry.

Experimentally reduced root-microbe interactions reveal limited plasticity in functional root traits in Acer and Quercus.

PubMed

Lee, Mei-Ho; Comas, Louise H; Callahan, Hilary S

2014-02-01

Interactions between roots and soil microbes are critical components of below-ground ecology. It is essential to quantify the magnitude of root trait variation both among and within species, including variation due to plasticity. In addition to contextualizing the magnitude of plasticity relative to differences between species, studies of plasticity can ascertain if plasticity is predictable and whether an environmental factor elicits changes in traits that are functionally advantageous. To compare functional traits and trait plasticities in fine root tissues with natural and reduced levels of colonization by microbial symbionts, trimmed and surface-sterilized root segments of 2-year-old Acer rubrum and Quercus rubra seedlings were manipulated. Segments were then replanted into satellite pots filled with control or heat-treated soil, both originally derived from a natural forest. Mycorrhizal colonization was near zero in roots grown in heat-treated soil; roots grown in control soil matched the higher colonization levels observed in unmanipulated root samples collected from field locations. Between-treatment comparisons revealed negligible plasticity for root diameter, branching intensity and nitrogen concentration across both species. Roots from treated soils had decreased tissue density (approx. 10-20 %) and increased specific root length (approx. 10-30 %). In contrast, species differences were significant and greater than treatment effects in traits other than tissue density. Interspecific trait differences were also significant in field samples, which generally resembled greenhouse samples. The combination of experimental and field approaches was useful for contextualizing trait plasticity in comparison with inter- and intra-specific trait variation. Findings that root traits are largely species dependent, with the exception of root tissue density, are discussed in the context of current literature on root trait variation, interactions with symbionts and recent progress in standardization of methods for quantifying root traits.

Root Exudation of Phytochemicals in Arabidopsis Follows Specific Patterns That Are Developmentally Programmed and Correlate with Soil Microbial Functions

PubMed Central

Sugiyama, Akifumi; Manter, Daniel K.; Vivanco, Jorge M.

2013-01-01

Plant roots constantly secrete compounds into the soil to interact with neighboring organisms presumably to gain certain functional advantages at different stages of development. Accordingly, it has been hypothesized that the phytochemical composition present in the root exudates changes over the course of the lifespan of a plant. Here, root exudates of in vitro grown Arabidopsis plants were collected at different developmental stages and analyzed using GC-MS. Principle component analysis revealed that the composition of root exudates varied at each developmental stage. Cumulative secretion levels of sugars and sugar alcohols were higher in early time points and decreased through development. In contrast, the cumulative secretion levels of amino acids and phenolics increased over time. The expression in roots of genes involved in biosynthesis and transportation of compounds represented in the root exudates were consistent with patterns of root exudation. Correlation analyses were performed of the in vitro root exudation patterns with the functional capacity of the rhizosphere microbiome to metabolize these compounds at different developmental stages of Arabidopsis grown in natural soils. Pyrosequencing of rhizosphere mRNA revealed strong correlations (p<0.05) between microbial functional genes involved in the metabolism of carbohydrates, amino acids and secondary metabolites with the corresponding compounds released by the roots at particular stages of plant development. In summary, our results suggest that the root exudation process of phytochemicals follows a developmental pattern that is genetically programmed. PMID:23383346

Root architecture impacts on root decomposition rates in switchgrass

NASA Astrophysics Data System (ADS)

de Graaff, M.; Schadt, C.; Garten, C. T.; Jastrow, J. D.; Phillips, J.; Wullschleger, S. D.

2010-12-01

Roots strongly contribute to soil organic carbon accrual, but the rate of soil carbon input via root litter decomposition is still uncertain. Root systems are built up of roots with a variety of different diameter size classes, ranging from very fine to very coarse roots. Since fine roots have low C:N ratios and coarse roots have high C:N ratios, root systems are heterogeneous in quality, spanning a range of different C:N ratios. Litter decomposition rates are generally well predicted by litter C:N ratios, thus decomposition of roots may be controlled by the relative abundance of fine versus coarse roots. With this study we asked how root architecture (i.e. the relative abundance of fine versus coarse roots) affects the decomposition of roots systems in the biofuels crop switchgrass (Panicum virgatum L.). To understand how root architecture affects root decomposition rates, we collected roots from eight switchgrass cultivars (Alamo, Kanlow, Carthage, Cave-in-Rock, Forestburg, Southlow, Sunburst, Blackwell), grown at FermiLab (IL), by taking 4.8-cm diameter soil cores from on top of the crown and directly next to the crown of individual plants. Roots were carefully excised from the cores by washing and analyzed for root diameter size class distribution using WinRhizo. Subsequently, root systems of each of the plants (4 replicates per cultivar) were separated in 'fine' (0-0.5 mm), 'medium' (0.5-1 mm) and 'coarse' roots (1-2.5 mm), dried, cut into 0.5 cm (medium and coarse roots) and 2 mm pieces (fine roots), and incubated for 90 days. For each of the cultivars we established five root-treatments: 20g of soil was amended with 0.2g of (1) fine roots, (2) medium roots, (3) coarse roots, (4) a 1:1:1 mixture of fine, medium and coarse roots, and (5) a mixture combining fine, medium and coarse roots in realistic proportions. We measured CO2 respiration at days 1, 3, 7, 15, 30, 60 and 90 during the experiment. The 13C signature of the soil was -26‰, and the 13C signature of plants was -12‰, enabling us to differentiate between root-derived C and native SOM-C respiration. We found that the relative abundance of fine, medium and coarse roots were significantly different among cultivars. Root systems of Alamo, Kanlow and Cave-in-Rock were characterized by a large abundance of coarse-, relative to fine roots, whereas Carthage, Forestburg and Blackwell had a large abundance of fine, relative to coarse roots. Fine roots had a 28% lower C:N ratio than medium and coarse roots. These differences led to different root decomposition rates. We conclude that root architecture should be taken into account when predicting root decomposition rates; enhanced understanding of the mechanisms of root decomposition will improve model predictions of C input to soil organic matter.

Root attributes affecting water uptake of rice (Oryza sativa) under drought

PubMed Central

Henry, Amelia

2012-01-01

Lowland rice roots have a unique physiological response to drought because of their adaptation to flooded soil. Rice root attributes that facilitate growth under flooded conditions may affect rice response to drought, but the relative roles of root structural and functional characteristics for water uptake under drought in rice are not known. Morphological, anatomical, biochemical, and molecular attributes of soil-grown rice roots were measured to investigate the genotypic variability and genotype×environment interactions of water uptake under variable soil water regimes. Drought-resistant genotypes had the lowest night-time bleeding rates of sap from the root system in the field. Diurnal fluctuation predominated as the strongest source of variation for bleeding rates in the field and root hydraulic conductivity (Lp r) in the greenhouse, and was related to expression trends of various PIP and TIP aquaporins. Root anatomy was generally more responsive to drought treatments in drought-resistant genotypes. Suberization and compaction of sclerenchyma layer cells decreased under drought, whereas suberization of the endodermis increased, suggesting differential roles of these two cell layers for the retention of oxygen under flooded conditions (sclerenchyma layer) and retention of water under drought (endodermis). The results of this study point to the genetic variability in responsiveness to drought of rice roots in terms of morphology, anatomy, and function. PMID:22791828

Root attributes affecting water uptake of rice (Oryza sativa) under drought.

PubMed

Henry, Amelia; Cal, Andrew J; Batoto, Tristram C; Torres, Rolando O; Serraj, Rachid

2012-08-01

Lowland rice roots have a unique physiological response to drought because of their adaptation to flooded soil. Rice root attributes that facilitate growth under flooded conditions may affect rice response to drought, but the relative roles of root structural and functional characteristics for water uptake under drought in rice are not known. Morphological, anatomical, biochemical, and molecular attributes of soil-grown rice roots were measured to investigate the genotypic variability and genotype×environment interactions of water uptake under variable soil water regimes. Drought-resistant genotypes had the lowest night-time bleeding rates of sap from the root system in the field. Diurnal fluctuation predominated as the strongest source of variation for bleeding rates in the field and root hydraulic conductivity (Lpr) in the greenhouse, and was related to expression trends of various PIP and TIP aquaporins. Root anatomy was generally more responsive to drought treatments in drought-resistant genotypes. Suberization and compaction of sclerenchyma layer cells decreased under drought, whereas suberization of the endodermis increased, suggesting differential roles of these two cell layers for the retention of oxygen under flooded conditions (sclerenchyma layer) and retention of water under drought (endodermis). The results of this study point to the genetic variability in responsiveness to drought of rice roots in terms of morphology, anatomy, and function.

Root-type-specific plasticity in response to localized high nitrate supply in maize (Zea mays)

PubMed Central

Yu, Peng; Hochholdinger, Frank; Li, Chunjian

2015-01-01

Background and Aims Shoot-borne roots contribute to most of the nutrient uptake throughout the life cycle of maize (Zea mays). Compared with numerous studies with embryonic roots, detailed information on the phenotypic plasticity of shoot-borne roots in response to a heterogeneous nitrogen supply is scarce. The present study therefore provides a comprehensive profile of fine-scale plastic responses of distinct root types to localized high nitrate supply. Methods Seedlings of the maize inbred line B73 were grown in split-root systems. The anatomy and morphological plasticity of the primary root and the roots initiated from the 2nd, 5th and 7th shoot nodes, and their lateral roots, were studied in response to local high nitrate supply to one side of the root system. Key Results In contrast to the insensitivity of axial roots, local high nitrate supply increased the length of 1st-order lateral roots on the primary root and the three whorls of shoot-borne roots at different growth stages, and increased the density of 1st-order lateral roots on the 7th shoot-borne root after silking. The length and density of 2nd-order lateral roots on the three whorls of shoot-borne roots displayed a more flexible response to local high nitrate than 1st-order lateral roots. Root diameter and number, and total area and diameter of metaxylem vessels increased from the primary root to early and then later developed shoot-borne roots, which showed a positive relationship with shoot growth and N accumulation. Conclusions Maize axial roots and lateral roots responded differently to local high nitrate, and this was related to their function. The extent of morphological plasticity of lateral roots in response to local high nitrate depended on the initiation time of the shoot-borne roots on which the lateral roots developed. Morphological plasticity was higher on 2nd-order than on 1st-order lateral roots. The results suggest that higher order lateral root branching might be a potential target for genetic improvement in future maize breeding. PMID:26346717

Dynamics of Aspen Roots Colonization by Pseudomonads Reveals Strain-Specific and Mycorrhizal-Specific Patterns of Biofilm Formation

PubMed Central

Noirot-Gros, Marie-Francoise; Shinde, Shalaka; Larsen, Peter E.; Zerbs, Sarah; Korajczyk, Peter J.; Kemner, Kenneth M.; Noirot, Philippe H.

2018-01-01

Rhizosphere-associated Pseudomonas fluorescens are known plant growth promoting (PGP) and mycorrhizal helper bacteria (MHB) of many plants and ectomycorrhizal fungi. We investigated the spatial and temporal dynamics of colonization of mycorrhizal and non-mycorrhizal Aspen seedlings roots by the P. fluorescens strains SBW25, WH6, Pf0-1, and the P. protegens strain Pf-5. Seedlings were grown in laboratory vertical plates systems, inoculated with a fluorescently labeled Pseudomonas strain, and root colonization was monitored over a period of 5 weeks. We observed unexpected diversity of bacterial assemblies on seedling roots that changed over time and were strongly affected by root mycorrhization. P. fluorescens SBW25 and WH6 stains developed highly structured biofilms with internal void spaces forming channels. On mycorrhizal roots bacteria appeared encased in a mucilaginous substance in which they aligned side by side in parallel arrangements. The different phenotypic classes of bacterial assemblies observed for the four Pseudomonas strains were summarized in a single model describing transitions between phenotypic classes. Our findings also reveal that bacterial assembly phenotypes are driven by interactions with mucilaginous materials present at roots. PMID:29774013

Circumnutation as an autonomous root movement in plants.

PubMed

Migliaccio, Fernando; Tassone, Paola; Fortunati, Alessio

2013-01-01

Although publications on circumnutation of the aerial parts of flowering plants are numerous and primarily from the time between Darwin (1880) and the 1950s, reports on circumnutation of roots are scarce. With the introduction of modern molecular biology techniques, many topics in the plant sciences have been revitalized; among these is root circumnutation. The most important research in this area has been done on Arabidopsis thaliana, which has roots that behave differently from those of many other plants; roots grown on inclined agar dishes produce a pattern of half waves slanted to one side. When grown instead on horizontally set dishes, the roots grow in loops or in tight right-handed coils that are characterized by a tight torsion to the left-hand. The roots of the few plants that differ from Arabidopsis and have been similarly tested do not present such patterns, because even if they circumnutate generally in a helical pattern, they subsequently straighten. Research on plants in space or on a clinostat has allowed the testing of these roots in a habitat lacking gravity or simulating the lack. Recently, molecular geneticists have started to connect various root behaviors to specific groups of genes. For example, anomalies in auxin responses caused by some genes can be overcome by complementation with wild-type genes. Such important studies contribute to understanding the mechanisms of growth and elongation, processes that are only superficially understood.

Characterization of plant growth promoting traits of bacterial isolates from the rhizosphere of barley (Hordeum vulgare L.) and tomato (Solanum lycopersicon L.) grown under Fe sufficiency and deficiency.

PubMed

Scagliola, M; Pii, Y; Mimmo, T; Cesco, S; Ricciuti, P; Crecchio, C

2016-10-01

Plant Growth Promoting Bacteria (PGPB) are considered a promising approach to replace the conventional agricultural practices, since they have been shown to affect plant nutrient-acquisition processes by influencing nutrient availability in the rhizosphere and/or those biochemical processes determining the uptake at root level of nitrogen (N), phosphorus (P), and iron (Fe), that represent the major constraints for crop productivity worldwide. We have isolated novel bacterial strains from the rhizosphere of barley (Hordeum vulgare L.) and tomato (Solanum lycopersicon L.) plants, previously grown in hydroponic solution (either Fe deficient or Fe sufficient) and subsequently transferred onto an agricultural calcareous soil. PGPB have been identified by molecular tools and characterized for their capacity to produce siderophores and indole-3-acetic acid (IAA), and to solubilize phosphate. Selected bacterial isolates, showing contemporarily high levels of the three activities investigated, were finally tested for their capacity to induce Fe reduction in cucumber roots two isolates, from barley and tomato plants under Fe deficiency, significantly increased the root Fe-chelate reductase activity; interestingly, another isolate enhanced the reduction of Fe-chelate reductase activity in cucumber plant roots, although grown under Fe sufficiency. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Molecular Physiology of Root System Architecture in Model Grasses

NASA Astrophysics Data System (ADS)

Hixson, K.; Ahkami, A. H.; Anderton, C.; Veličković, D.; Myers, G. L.; Chrisler, W.; Lindenmaier, R.; Fang, Y.; Yabusaki, S.; Rosnow, J. J.; Farris, Y.; Khan, N. E.; Bernstein, H. C.; Jansson, C.

2017-12-01

Unraveling the molecular and physiological mechanisms involved in responses of Root System Architecture (RSA) to abiotic stresses and shifts in microbiome structure is critical to understand and engineer plant-microbe-soil interactions in the rhizosphere. In this study, accessions of Brachypodium distachyon Bd21 (C3 model grass) and Setaria viridis A10.1 (C4 model grass) were grown in phytotron chambers under current and elevated CO2 levels. Detailed growth stage-based phenotypic analysis revealed different above- and below-ground morphological and physiological responses in C3 and C4 grasses to enhanced CO2 levels. Based on our preliminary results and by screening values of total biomass, water use efficiency, root to shoot ratio, RSA parameters and net assimilation rates, we postulated a three-phase physiological mechanism, i.e. RootPlus, BiomassPlus and YieldPlus phases, for grass growth under elevated CO2 conditions. Moreover, this comprehensive set of morphological and process-based observations are currently in use to develop, test, and calibrate biophysical whole-plant models and in particular to simulate leaf-level photosynthesis at various developmental stages of C3 and C4 using the model BioCro. To further link the observed phenotypic traits at the organismal level to tissue and molecular levels, and to spatially resolve the origin and fate of key metabolites involved in primary carbohydrate metabolism in different root sections, we complement root phenotypic observations with spatial metabolomics data using mass spectrometry imaging (MSI) methods. Focusing on plant-microbe interactions in the rhizosphere, six bacterial strains with plant growth promoting features are currently in use in both gel-based and soil systems to screen root growth and development in Brachypodium. Using confocal microscopy, GFP-tagged bacterial systems are utilized to study the initiation of different root types of RSA, including primary root (PR), coleoptile node axile root (CNR) and leaf node axile root (LNR) during developmental stages of root formation. The root exudates also will be quantified and preliminary data will be used to engineer our microbial consortium to improve plant growth.

A comparison of sole carbon source utilization patterns and phospholipid fatty acid profiles to detect changes in the root microflora of hydroponically grown crops.

PubMed

Khalil, S; Bååth, E; Alsanius, B; Englund, J E; Sundin, P; Gertsson, U E; Jensén, P

2001-04-01

Sole carbon source utilization (SCSU) patterns and phospholipid fatty acid (PLFA) profiles were compared with respect to their potential to characterize root-inhabiting microbial communities of hydroponically grown crops. Sweet pepper (Capsicum annum cv. Evident), lettuce (Lactuca sativa cv. Grand Rapids), and four different cultivars of tomato (Lycopersicon esculentum cvs. Gitana, Armada, Aromata, and Elin) were grown in 1-L black plastic beakers placed in a cultivation chamber with artificial light. In addition to the harvest of the plants after 6 weeks, plants of one tomato cultivar, cv. Gitana, were also harvested after 4 and 8 weeks. The cultivation in this study was performed twice. Principal component analysis was used to analyze the data. Both characterization methods had the ability to discriminate between the root microflora of different plant species, cultivars, and one tomato cultivar at different ages. Differences in both SCSU patterns and PLFA profiles were larger between plant species than between cultivars, but for both methods the largest differences were between the two cultivations. Still, the differences between treatments were always due to differences in the same PLFAs in both cultivations. This was not the case for the SCSU patterns when different plant ages were studied. Furthermore, PLFA profiles showed less variation between replicates than did SCSU patterns. This larger variation observed among the SCSU data indicates that PLFA may be more useful to detect changes in the root microflora of hydroponically grown crops than the SCSU technique.

Temperature sensing by primary roots of maize

NASA Technical Reports Server (NTRS)

Poff, K. L.

1990-01-01

Zea mays L. seedlings, grown on agar plates at 26 degrees C, reoriented the original vertical direction of their primary root when exposed to a thermal gradient applied perpendicular to the gravity vector. The magnitude and direction of curvature can not be explained simply by either a temperature or a humidity effect on root elongation. It is concluded that primary roots of maize sense temperature gradients in addition to sensing the gravitational force.

Cadmium-Induced Changes in Antioxidative Systems, Hydrogen Peroxide Content, and Differentiation in Scots Pine Roots1

PubMed Central

Schützendübel, Andres; Schwanz, Peter; Teichmann, Thomas; Gross, Kristina; Langenfeld-Heyser, Rosemarie; Godbold, Douglas L.; Polle, Andrea

2001-01-01

To investigate whether Cd induces common plant defense pathways or unspecific necrosis, the temporal sequence of physiological reactions, including hydrogen peroxide (H2O2) production, changes in ascorbate-glutathione-related antioxidant systems, secondary metabolism (peroxidases, phenolics, and lignification), and developmental changes, was characterized in roots of hydroponically grown Scots pine (Pinus sylvestris) seedlings. Cd (50 μm, 6 h) initially increased superoxide dismutase, inhibited the systems involved in H2O2 removal (glutathione/glutathione reductase, catalase [CAT], and ascorbate peroxidase [APX]), and caused H2O2 accumulation. Elongation of the roots was completely inhibited within 12 h. After 24 h, glutathione reductase activities recovered to control levels; APX and CAT were stimulated by factors of 5.5 and 1.5. Cell death was increased. After 48 h, nonspecific peroxidases and lignification were increased, and APX and CAT activities were decreased. Histochemical analysis showed that soluble phenolics accumulated in the cytosol of Cd-treated roots but lignification was confined to newly formed protoxylem elements, which were found in the region of the root tip that normally constitutes the elongation zone. Roots exposed to 5 μm Cd showed less pronounced responses and only a small decrease in the elongation rate. These results suggest that in cells challenged by Cd at concentrations exceeding the detoxification capacity, H2O2 accumulated because of an imbalance of redox systems. This, in turn, may have triggered the developmental program leading to xylogenesis. In conclusion, Cd did not cause necrotic injury in root tips but appeared to expedite differentiation, thus leading to accelerated aging. PMID:11706171

Breeding cassava for higher yield

USDA-ARS?s Scientific Manuscript database

Cassava is a root crop grown for food and for starch production. Breeding progress is slowed by asexual production and high levels of heterozygosity. Germplasm resources are rich and accessible to breeders through genebanks worldwide. Breeding objectives include high root yield, yield stability, dis...

Response of millet and sorghum to a varying water supply around the primary and nodal roots

PubMed Central

Rostamza, M.; Richards, R. A.; Watt, M.

2013-01-01

Background and Aims Cereals have two root systems. The primary system originates from the embryo when the seed germinates and can support the plant until it produces grain. The nodal system can emerge from stem nodes throughout the plant's life; its value for yield is unclear and depends on the environment. The aim of this study was to test the role of nodal roots of sorghum and millet in plant growth in response to variation in soil moisture. Sorghum and millet were chosen as both are adapted to dry conditions. Methods Sorghum and millet were grown in a split-pot system that allowed the primary and nodal roots to be watered separately. Key Results When primary and nodal roots were watered (12 % soil water content; SWC), millet nodal roots were seven times longer than those of sorghum and six times longer than millet plants in dry treatments, mainly from an 8-fold increase in branch root length. When soil was allowed to dry in both compartments, millet nodal roots responded and grew 20 % longer branch roots than in the well-watered control. Sorghum nodal roots were unchanged. When only primary roots received water, nodal roots of both species emerged and elongated into extremely dry soil (0·6–1·5 % SWC), possibly with phloem-delivered water from the primary roots in the moist inner pot. Nodal roots were thick, short, branchless and vertical, indicating a tropism that was more pronounced in millet. Total nodal root length increased in both species when the dry soil was covered with plastic, suggesting that stubble retention or leaf mulching could facilitate nodal roots reaching deeper moist layers in dry climates. Greater nodal root length in millet than in sorghum was associated with increased shoot biomass, water uptake and water use efficiency (shoot mass per water). Millet had a more plastic response than sorghum to moisture around the nodal roots due to (1) faster growth and progression through ontogeny for earlier nodal root branch length and (2) partitioning to nodal root length from primary roots, independent of shoot size. Conclusions Nodal and primary roots have distinct responses to soil moisture that depend on species. They can be selected independently in a breeding programme to shape root architecture. A rapid rate of plant development and enhanced responsiveness to local moisture may be traits that favour nodal roots and water use efficiency at no cost to shoot growth. PMID:23749473

Response of millet and sorghum to a varying water supply around the primary and nodal roots.

PubMed

Rostamza, M; Richards, R A; Watt, M

2013-07-01

Cereals have two root systems. The primary system originates from the embryo when the seed germinates and can support the plant until it produces grain. The nodal system can emerge from stem nodes throughout the plant's life; its value for yield is unclear and depends on the environment. The aim of this study was to test the role of nodal roots of sorghum and millet in plant growth in response to variation in soil moisture. Sorghum and millet were chosen as both are adapted to dry conditions. Sorghum and millet were grown in a split-pot system that allowed the primary and nodal roots to be watered separately. When primary and nodal roots were watered (12 % soil water content; SWC), millet nodal roots were seven times longer than those of sorghum and six times longer than millet plants in dry treatments, mainly from an 8-fold increase in branch root length. When soil was allowed to dry in both compartments, millet nodal roots responded and grew 20 % longer branch roots than in the well-watered control. Sorghum nodal roots were unchanged. When only primary roots received water, nodal roots of both species emerged and elongated into extremely dry soil (0.6-1.5 % SWC), possibly with phloem-delivered water from the primary roots in the moist inner pot. Nodal roots were thick, short, branchless and vertical, indicating a tropism that was more pronounced in millet. Total nodal root length increased in both species when the dry soil was covered with plastic, suggesting that stubble retention or leaf mulching could facilitate nodal roots reaching deeper moist layers in dry climates. Greater nodal root length in millet than in sorghum was associated with increased shoot biomass, water uptake and water use efficiency (shoot mass per water). Millet had a more plastic response than sorghum to moisture around the nodal roots due to (1) faster growth and progression through ontogeny for earlier nodal root branch length and (2) partitioning to nodal root length from primary roots, independent of shoot size. Nodal and primary roots have distinct responses to soil moisture that depend on species. They can be selected independently in a breeding programme to shape root architecture. A rapid rate of plant development and enhanced responsiveness to local moisture may be traits that favour nodal roots and water use efficiency at no cost to shoot growth.

Feedbacks between soil penetration resistance, root architecture and water uptake limit water accessibility and crop growth - A vicious circle.

PubMed

Colombi, Tino; Torres, Lorena Chagas; Walter, Achim; Keller, Thomas

2018-06-01

Water is the most limiting resource for global crop production. The projected increase of dry spells due to climate change will further increase the problem of water limited crop yields. Besides low water abundance and availability, water limitations also occur due to restricted water accessibility. Soil penetration resistance, which is largely influenced by soil moisture, is the major soil property regulating root elongation and water accessibility. Until now the interactions between soil penetration resistance, root system properties, water uptake and crop productivity are rarely investigated. In the current study we quantified how interactive effects between soil penetration resistance, root architecture and water uptake affect water accessibility and crop productivity in the field. Maize was grown on compacted and uncompacted soil that was either tilled or remained untilled after compaction, which resulted in four treatments with different topsoil penetration resistance. Higher topsoil penetration resistance caused root systems to be shallower. This resulted in increased water uptake from the topsoil and hence topsoil drying, which further increased the penetration resistance in the uppermost soil layer. As a consequence of this feedback, root growth into deeper soil layers, where water would have been available, was reduced and plant growth decreased. Our results demonstrate that soil penetration resistance, root architecture and water uptake are closely interrelated and thereby determine the potential of plants to access soil water pools. Hence, these interactions and their feedbacks on water accessibility and crop productivity have to be accounted for when developing strategies to alleviate water limitations in cropping systems. Copyright © 2018 Elsevier B.V. All rights reserved.

A nonpathogenic Fusarium oxysporum strain enhances phytoextraction of heavy metals by the hyperaccumulator Sedum alfredii Hance.

PubMed

Zhang, Xincheng; Lin, Li; Chen, Mingyue; Zhu, Zhiqiang; Yang, Weidong; Chen, Bao; Yang, Xiaoe; An, Qianli

2012-08-30

Low biomass and shallow root systems limit the application of heavy metal phytoextraction by hyperaccumulators. Plant growth-promoting microbes may enhance hyperaccumulators'phytoextraction. A heavy metal-resistant fungus belonged to the Fusarium oxysporum complex was isolated from the Zn/Cd co-hyperaccumulator Sedum alfredii Hance grown in a Pb/Zn mined area. This Fusarium fungus was not pathogenic to plants but promoted host growth. Hydroponic experiments showed that 500 μM Zn(2+) or 50 μM Cd(2+) combined with the fungus increased root length, branches, and surface areas, enhanced nutrient uptake and chlorophyll synthesis, leading to more vigorous hyperaccumulators with greater root systems. Soil experiments showed that the fungus increased root and shoot biomass and S. alfredii-mediated heavy metal availabilities, uptake, translocation or concentrations, and thus increased phytoextraction of Zn (144% and 44%), Cd (139% and 55%), Pb (84% and 85%) and Cu (63% and 77%) from the original Pb/Zn mined soil and a multi-metal contaminated paddy soil. Together, the nonpathogenic Fusarium fungus was able to increase S. alfredii root systems and function, metal availability and accumulation, plant biomass, and thus phytoextraction efficiency. This study showed a great application potential for culturable indigenous fungi other than symbiotic mycorrhizas to enhance the phytoextraction by hyperaccumulators. Copyright © 2012 Elsevier B.V. All rights reserved.

Unraveling the hydrodynamics of split root water uptake experiments using CT scanned root architectures and three dimensional flow simulations

PubMed Central

Koebernick, Nicolai; Huber, Katrin; Kerkhofs, Elien; Vanderborght, Jan; Javaux, Mathieu; Vereecken, Harry; Vetterlein, Doris

2015-01-01

Split root experiments have the potential to disentangle water transport in roots and soil, enabling the investigation of the water uptake pattern of a root system. Interpretation of the experimental data assumes that water flow between the split soil compartments does not occur. Another approach to investigate root water uptake is by numerical simulations combining soil and root water flow depending on the parameterization and description of the root system. Our aim is to demonstrate the synergisms that emerge from combining split root experiments with simulations. We show how growing root architectures derived from temporally repeated X-ray CT scanning can be implemented in numerical soil-plant models. Faba beans were grown with and without split layers and exposed to a single drought period during which plant and soil water status were measured. Root architectures were reconstructed from CT scans and used in the model R-SWMS (root-soil water movement and solute transport) to simulate water potentials in soil and roots in 3D as well as water uptake by growing roots in different depths. CT scans revealed that root development was considerably lower with split layers compared to without. This coincided with a reduction of transpiration, stomatal conductance and shoot growth. Simulated predawn water potentials were lower in the presence of split layers. Simulations showed that this was related to an increased resistance to vertical water flow in the soil by the split layers. Comparison between measured and simulated soil water potentials proved that the split layers were not perfectly isolating and that redistribution of water from the lower, wetter compartments to the drier upper compartments took place, thus water losses were not equal to the root water uptake from those compartments. Still, the layers increased the resistance to vertical flow which resulted in lower simulated collar water potentials that led to reduced stomatal conductance and growth. PMID:26074935

Structure, variation, and assembly of the root-associated microbiomes of rice

PubMed Central

Edwards, Joseph; Johnson, Cameron; Santos-Medellín, Christian; Lurie, Eugene; Podishetty, Natraj Kumar; Bhatnagar, Srijak; Eisen, Jonathan A.; Sundaresan, Venkatesan

2015-01-01

Plants depend upon beneficial interactions between roots and microbes for nutrient availability, growth promotion, and disease suppression. High-throughput sequencing approaches have provided recent insights into root microbiomes, but our current understanding is still limited relative to animal microbiomes. Here we present a detailed characterization of the root-associated microbiomes of the crop plant rice by deep sequencing, using plants grown under controlled conditions as well as field cultivation at multiple sites. The spatial resolution of the study distinguished three root-associated compartments, the endosphere (root interior), rhizoplane (root surface), and rhizosphere (soil close to the root surface), each of which was found to harbor a distinct microbiome. Under controlled greenhouse conditions, microbiome composition varied with soil source and genotype. In field conditions, geographical location and cultivation practice, namely organic vs. conventional, were factors contributing to microbiome variation. Rice cultivation is a major source of global methane emissions, and methanogenic archaea could be detected in all spatial compartments of field-grown rice. The depth and scale of this study were used to build coabundance networks that revealed potential microbial consortia, some of which were involved in methane cycling. Dynamic changes observed during microbiome acquisition, as well as steady-state compositions of spatial compartments, support a multistep model for root microbiome assembly from soil wherein the rhizoplane plays a selective gating role. Similarities in the distribution of phyla in the root microbiomes of rice and other plants suggest that conclusions derived from this study might be generally applicable to land plants. PMID:25605935

Stock Type Affects Performance of Shortleaf Pine Planted in the Ouachita Mountains Through 10 Years

Treesearch

James P. Barnett; John C. Brissette

2004-01-01

Shortleaf pine (Pinus echinata Mill.) seeds collected from several half-sib families were grown as both bare-root and container stock and outplanted on two sites in the Ouachita Mountains of Arkansas. When outplanted, the bare-root seedlings had greater mean height and root-collar diameter than the container seedlings. However, the container...

Seasonal patterns of CO2 exchange in the shoot and root of loblolly pine seedlings

Treesearch

Allen P. Drew; F. Thomas Ledig

1981-01-01

Seedlings of six full-sib families of loblolly pine were grown outdoors in clay pots for two growing seasons. Dark respiration of shoot and root and CO2 exchange of the shoot in the light were measured periodically over a temperature range bracketing ambient conditions. Both shoot and root showed different physiological responses as seasonal...

Mind the Roots: Phenotyping Below-Ground Crop Diversity and Its Influence on Final Yield

NASA Astrophysics Data System (ADS)

Nieters, C.; Guadagno, C. R.; Lemli, S.; Hosseini, A.; Ewers, B. E.

2017-12-01

Changes in global climate patterns and water regimes are having profound impacts on worldwide crop production. An ever-growing population paired with increasing temperatures and unpredictable periods of severe drought call for accurate modeling of future crop yield. Although novel approaches are being developed in high-throughput, above-ground image phenotyping, the below-ground plant system is still poorly phenotyped. Collection of plant root morphology and hydraulics are needed to inform mathematical models to reliably estimate yields of crops grown in sub-optimal conditions. We used Brassica rapa to inform our model as it is a globally cultivated crop with several functionally diverse cultivars. Specifically, we use 7 different accessions from oilseed (R500 and Yellow Sarson), leafy type (Pac choi and Chinese cabbage), a vegetable turnip, and two Wisconsin Fast Plants (Imb211 and Fast Plant self-compatible), which have shorter life cycles and potentially large differences in allocation to roots. Bi-weekly, we harvested above and below-ground biomass to compare the varieties in terms of carbon allocation throughout their life cycle. Using WinRhizo software, we analyzed root system length and surface area to compare and contrast root morphology among cultivars. Our results confirm that root structural characteristics are crucial to explain plant water use and carbon allocation. The root:shoot ratio reveals a significant (p < 0.01) difference among crop accession. To validate the procedure across different varieties and life stages we also compared surface area results from the image-based technology to dry biomass finding a strong linear relationship (R2= 0.85). To assess the influence of a diverse above-ground morphology on the root system we also measured above-ground anatomical and physiological traits such as gas exchange, chlorophyll content, and chlorophyll a fluorescence. A thorough analysis of the root system will clarify carbon dynamics and hydraulics at the whole-plant level, improving final yield predictions.

Active carbon-pools in rhizosphere of wheat (Triticum aestivum L.) grown under elevated atmospheric carbon dioxide concentration in a Typic Haplustept in sub-tropical India.

PubMed

Kant, Pratap C B; Bhadraray, Subhendu; Purakayastha, T J; Jain, Vanita; Pal, Madan; Datta, S C

2007-05-01

Study on active and labile carbon-pools can serve as a clue for soil organic carbon dynamics on exposure to elevated level of CO2. Therefore, an experimental study was conducted in a Typic Haplustept in sub-tropical semi-arid India with wheat grown in open top chambers at ambient (370 micromol mol-1) and elevated (600 micromol mol-1) concentrations of atmospheric CO2. Elevated atmospheric CO2 caused increase in yield and carbon uptake by all plant parts, and their preferential partitioning to root. Increases in fresh root weight, volume and length have also been observed. Relative contribution of medium-sized root to total root length increased at the expense of very fine roots at elevated CO2 level. All active carbon-fractions gained due to elevated atmospheric CO2 concentration, and the order followed their relative labilities. All the C-pools have recorded a significant increase over initial status, and are expected to impart short-to-medium-term effect on soil carbon sequestration.

Automorphosis of higher plants on a 3-D clinostat

NASA Astrophysics Data System (ADS)

Hoson, T.; Kamisaka, S.; Yamashita, M.; Masuda, Y.

On a three-dimensional (3-D) clinostat, various plant organs developed statocytes capable of responding to the gravity vector. The graviresponse of primary roots of garden cress and maize grown on the clinostat was the same as the control roots, whereas that of maize coleoptiles was reduced. When maize seedlings were grown in the presence of 10^-4 M gibberellic acid and kinetin, the graviresponse of both roots and shoots was suppressed. The corresponding suppression of amyloplast development was observed in the clinostatted and the hormone-treated seedlings. Maize roots and shoots showed spontaneous curvatures in different portions on the 3-D clinostat. The hormone treatment did not significantly influence such an automorphic curvature. When the root cap was removed, maize roots did not curve gravitropically. However, the removal suppressed the automorphic curvatures only slightly. On the other hand, the removal of coleoptile tip did not influence its graviresponse, whereas the spontaneous curvature of decapitated coleoptiles on the clinostat was strongly suppressed. Also, cytochalasin B differently affected the gravitropic and the automorphic curvatures of maize roots and shoots. From these results it is concluded that the graviperception and the early processes of signal transmission are unnecessary for automorphoses under simulated microgravity conditions. Moreover, the results support the view that the amyloplasts act as statoliths probably via an interaction with microfilaments.

Integration of root phenes revealed by intensive phenotyping of root system architecture, anatomy, and physiology in cereals

NASA Astrophysics Data System (ADS)

York, Larry

2015-04-01

Food insecurity is among the greatest challenges humanity will face in the 21st century. Agricultural production in much of the world is constrained by the natural infertility of soil which restrains crops from reaching their yield potential. In developed nations, fertilizer inputs pollute air and water and contribute to climate change and environmental degradation. In poor nations low soil fertility is a primary constraint to food security and economic development. Water is almost always limiting crop growth in any system. Increasing the acquisition efficiency of soil resources is one method by which crop yields could be increased without the use of more fertilizers or irrigation. Cereals are the most widely grown crops, both in terms of land area and in yield, so optimizing uptake efficiency of cereals is an important goal. Roots are the primary interface between plant and soil and are responsible for the uptake of soil resources. The deployment of roots in space and time comprises root system architecture (RSA). Cereal RSA is a complex phenotype that aggregates many elemental phenes (elemental units of phenotype). Integration of root phenes will be determined by interactions through their effects on soil foraging and plant metabolism. Many architectural, metabolic, and physiological root phenes have been identified in maize, including: nodal root number, nodal root growth angle, lateral root density, lateral root length, aerenchyma, cortical cell size and number, and nitrate uptake kinetics. The utility of these phenes needs confirmation in maize and in other cereals. The maize root system is composed of an embryonic root system and nodal roots that emerge in successive whorls as the plant develops, and is similar to other cereals. Current phenotyping platforms often ignore the inner whorls and instead focus on the most visible outer whorls after excavating a maize root crown from soil. Here, an intensive phenotyping platform evaluating phenes of all nodal root whorls in maize is introduced, and field work demonstrated how the variation within the root crown has functional significance for nitrogen acquisition. Nodal root number was decomposed to more elemental phenes including the number of nodes and the occupancies of each node. Simulations demonstrated that root systems forming fewer nodal roots and with delayed emergence perform well in low nitrogen soils. Nitrate uptake kinetics (NUK) also varied within the maize root system, and simulations showing a lack of interaction between NUK and RSA reflects a knowledge gap in the costs of NUK at the molecular level. Finally, maize RSA among hybrids from different era periods over the past 100 years suggests evolution towards more nitrogen efficient root phene states. This work will be discussed within the context of next-generation root phenotyping of cereals, the dilemma between extensive and intensive phenotyping, and the need for linking across scales and methods.

Improved sustainability of feedstock production with sludge and interacting mycorrhiza.

PubMed

Seleiman, Mahmoud F; Santanen, Arja; Kleemola, Jouko; Stoddard, Frederick L; Mäkelä, Pirjo S A

2013-05-01

Recycling nutrients saves energy and improves agricultural sustainability. Sewage sludge contains 2.6% P and 3.1% N, so the availability of these nutrients was investigated using four crops grown in either soil or sand. Further attention was paid to the role of mycorrhiza in improvement of nutrient availability. The content of heavy metals and metalloids in the feedstock was analyzed. Sewage sludge application resulted in greater biomass accumulation in ryegrass than comparable single applications of either synthetic fertilizer or digested sludge. Sewage sludge application resulted in more numerous mycorrhizal spores in soil and increased root colonization in comparison to synthetic fertilizer. All plants studied had mycorrhizal colonized roots, with the highest colonization rate in maize, followed by hemp. Sewage sludge application resulted in the highest P uptake in all soil-grown plants. In conclusion, sewage sludge application increased feedstock yield, provided beneficial use for organic wastes, and contributed to the sustainability of bioenergy feedstock production systems. It also improves the soil conditions and plant nutrition through colonization by mycorrhizal fungi as well as reducing leaching and need of synthetic fertilizers. Copyright © 2013 Elsevier Ltd. All rights reserved.

Enhanced formation of aerenchyma and induction of a barrier to radial oxygen loss in adventitious roots of Zea nicaraguensis contribute to its waterlogging tolerance as compared with maize (Zea mays ssp. mays).

PubMed

Abiko, Tomomi; Kotula, Lukasz; Shiono, Katsuhiro; Malik, Al Imran; Colmer, Timothy David; Nakazono, Mikio

2012-09-01

Enhancement of oxygen transport from shoot to root tip by the formation of aerenchyma and also a barrier to radial oxygen loss (ROL) in roots is common in waterlogging-tolerant plants. Zea nicaraguensis (teosinte), a wild relative of maize (Zea mays ssp. mays), grows in waterlogged soils. We investigated the formation of aerenchyma and ROL barrier induction in roots of Z. nicaraguensis, in comparison with roots of maize (inbred line Mi29), in a pot soil system and in hydroponics. Furthermore, depositions of suberin in the exodermis/hypodermis and lignin in the epidermis of adventitious roots of Z. nicaraguensis and maize grown in aerated or stagnant deoxygenated nutrient solution were studied. Growth of maize was more adversely affected by low oxygen in the root zone (waterlogged soil or stagnant deoxygenated nutrient solution) compared with Z. nicaraguensis. In stagnant deoxygenated solution, Z. nicaraguensis was superior to maize in transporting oxygen from shoot base to root tip due to formation of larger aerenchyma and a stronger barrier to ROL in adventitious roots. The relationships between the ROL barrier formation and suberin and lignin depositions in roots are discussed. The ROL barrier, in addition to aerenchyma, would contribute to the waterlogging tolerance of Z. nicaraguensis. © 2012 Blackwell Publishing Ltd.

Organ specificity in the plant circadian system is explained by different light inputs to the shoot and root clocks.

PubMed

Bordage, Simon; Sullivan, Stuart; Laird, Janet; Millar, Andrew J; Nimmo, Hugh G

2016-10-01

Circadian clocks allow the temporal compartmentalization of biological processes. In Arabidopsis, circadian rhythms display organ specificity but the underlying molecular causes have not been identified. We investigated the mechanisms responsible for the similarities and differences between the clocks of mature shoots and roots in constant conditions and in light : dark cycles. We developed an imaging system to monitor clock gene expression in shoots and light- or dark-grown roots, modified a recent mathematical model of the Arabidopsis clock and used this to simulate our new data. We showed that the shoot and root circadian clocks have different rhythmic properties (period and amplitude) and respond differently to light quality. The root clock was entrained by direct exposure to low-intensity light, even in antiphase to the illumination of shoots. Differences between the clocks were more pronounced in conditions where light was present than in constant darkness, and persisted in the presence of sucrose. We simulated the data successfully by modifying those parameters of a clock model that are related to light inputs. We conclude that differences and similarities between the shoot and root clocks can largely be explained by organ-specific light inputs. This provides mechanistic insight into the developing field of organ-specific clocks. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

Tree growth and management in Ugandan agroforestry systems: effects of root pruning on tree growth and crop yield.

PubMed

Wajja-Musukwe, Tellie-Nelson; Wilson, Julia; Sprent, Janet I; Ong, Chin K; Deans, J Douglas; Okorio, John

2008-02-01

Tree root pruning is a potential tool for managing belowground competition when trees and crops are grown together in agroforestry systems. We investigated the effects of tree root pruning on shoot growth and root distribution of Alnus acuminata (H.B. & K.), Casuarina equisetifolia L., Grevillea robusta A. Cunn. ex R. Br., Maesopsis eminii Engl. and Markhamia lutea (Benth.) K. Schum. and on yield of adjacent crops in sub-humid Uganda. The trees were 3 years old at the commencement of the study, and most species were competing strongly with crops. Tree roots were pruned 41 months after planting by cutting and back-filling a trench to a depth of 0.3 m, at a distance of 0.3 m from the trees, on one side of the tree row. The trench was reopened and roots recut at 50 and 62 months after planting. We assessed the effects on tree growth and root distribution over a 3 year period, and crop yield after the third root pruning at 62 months. Overall, root pruning had only a slight effect on aboveground tree growth: height growth was unaffected and diameter growth was reduced by only 4%. A substantial amount of root regrowth was observed by 11 months after pruning. Tree species varied in the number and distribution of roots, and C. equisetifolia and M. lutea had considerably more roots per unit of trunk volume than the other species, especially in the surface soil layers. Casuarina equisetifolia and M. eminii were the tree species most competitive with crops and G. robusta and M. lutea the least competitive. Crop yield data provided strong evidence of the redistribution of root activity following root pruning, with competition increasing on the unpruned side of tree rows. Thus, one-sided root pruning will be useful in only a few circumstances.

A novel gene whose expression in Medicago truncatula roots is suppressed in response to colonization by vesicular-arbuscular mycorrhizal (VAM) fungi and to phosphate nutrition.

PubMed

Burleigh, S H; Harrison, M J

1997-05-01

A cDNA clone (Mt4) was isolated as a result of a differential screen to identify genes showing altered expression during the interaction between Medicago truncatula and the vesicular-arbuscular mycorrhizal (VAM) fungus Glomus versiforme. Mt4 represents a M. truncatula mRNA that contains numerous short open reading frames, the two longest of which are predicted to encode polypeptides of 51 amino acids each. One of these open reading frames shares a short region of identity with a phosphate starvation-inducible gene from tomato. Mt4 gene expression is regulated in response to colonization by mycorrhizal fungi: transcripts were detected in non-colonized roots and levels decreased in both M. truncatula and M. sativa (alfalfa) roots after colonization by G. versiforme. Transcript levels also decreased during the incomplete interaction between G. versiforme and a M. sativa mycorrhizal minus (myc-) line, indicating that the down-regulation of this gene occurs early during the interaction between the fungus and its host plant. Phosphate levels in the nutrient media also affected the expression of the Mt4 gene: transcripts were present in the roots of plants grown under phosphate-deficient conditions, but were undetectable in the roots of plants grown under phosphate sufficient conditions. Furthermore, expression was only observed when plants were grown under nitrogen-sufficient conditions. Northern blot analyses indicate that Mt4 transcripts are present primarily in roots and barely detectable in stems or leaves. Thus, Mt4 represents a M. truncatula gene whose expression is regulated in response to both colonization by mycorrhizal fungi and to the phosphate status of the plant.

Intensive field phenotyping of maize (Zea mays L.) root crowns identifies phenes and phene integration associated with plant growth and nitrogen acquisition

PubMed Central

York, Larry M.; Lynch, Jonathan P.

2015-01-01

Root architecture is an important regulator of nitrogen (N) acquisition. Existing methods to phenotype the root architecture of cereal crops are generally limited to seedlings or to the outer roots of mature root crowns. The functional integration of root phenes is poorly understood. In this study, intensive phenotyping of mature root crowns of maize was conducted to discover phenes and phene modules related to N acquisition. Twelve maize genotypes were grown under replete and deficient N regimes in the field in South Africa and eight in the USA. An image was captured for every whorl of nodal roots in each crown. Custom software was used to measure root phenes including nodal occupancy, angle, diameter, distance to branching, lateral branching, and lateral length. Variation existed for all root phenes within maize root crowns. Size-related phenes such as diameter and number were substantially influenced by nodal position, while angle, lateral density, and distance to branching were not. Greater distance to branching, the length from the shoot to the emergence of laterals, is proposed to be a novel phene state that minimizes placing roots in already explored soil. Root phenes from both older and younger whorls of nodal roots contributed to variation in shoot mass and N uptake. The additive integration of root phenes accounted for 70% of the variation observed in shoot mass in low N soil. These results demonstrate the utility of intensive phenotyping of mature root systems, as well as the importance of phene integration in soil resource acquisition. PMID:26041317

Shade periodicity affects growth of container grown dogwoods

USDA-ARS?s Scientific Manuscript database

Container-grown dogwoods rank third in the US in nursery sales of ornamental trees. However, Dogwoods are a challenging crop to produce in container culture, especially when bare root liners are used as the initial transplant into containers due unacceptable levels of mortality and poor growth. This...

The effect of iron plaque on lead translocation in soil-Carex cinerascens kukenth. system.

PubMed

Liu, Chunying; Gong, Xiaofeng; Chen, Chunli; Yang, Juyun; Xu, Sheng

2016-01-01

A pot experiment was conducted to investigate the effect of iron plaque on Pb uptake by and translocation in Carex cinerascens Kukenth. grown under open-air conditions. Using Scanning Electron Microscopy and Energy Dispersive X-Ray Spectrometry, iron plaque was present as an amorphous coating on root surfaces with uneven distribution. The amount of iron plaque increased significantly with increasing Fe additions regardless of Pb additions. The presence of iron plaque on the root surface of Carex cinerascens Kukenth. increased the concentrations of Pb adsorbed by iron plaque. The Pb percentage in whole roots increased by 14.52% at 500 mg kg(-1) Fe treatment than at 0 mg kg(-1) Fe, and the distribution coefficient (DC) of Pb and translocation factor (TF) root increased with Fe additions, but translocation factor (TF) shoot decreased with Fe additions. The results suggested that iron plaque could promote the translocation of Pb from soil to roots to some extent, and it played a role to reduce heavy metals pollution of Poyang Lake wetland.

BioChar Amendments for Improved Plant Microbiome and Crop Health Project

NASA Technical Reports Server (NTRS)

Zeitlin, Nancy; Smith, David; Catechis, John; Khodadad, Christina; Koss, Lawrence; Mejia, Oscar Monje; Spencer, Lashelle

2015-01-01

Plant-based Environmental Control and Life Support Systems (ECLSS) enable human existence beyond Low Earth Orbit (LEO) by providing oxygen, water and food. The root modules are key to success of sustainable plant-based ECLSS. In microgravity, hydroponics is not viable as gases separate from fluids, thus plants are grown in soil substrates, which are bulky and must be maintained for optimal plant growth. Soil substrate selection also impacts ECLSS self-sufficiency. Savings in resupply mass and volume are possible if soil is developed in-situ from regolith found on moons or planets. Biochar, a soil amendment used by ancient civilizations to improve soil fertility that promotes plant health and root zone microbes, can be produced by pyrolysis of plant biomass. The goal is to study the effect of biochar on sequential crop plantings in a single root module. The objectives are: 1) follow changes in root-microbe interactions using metagenomic techniques, 2) measure changes in microbial populations during sequential cropping in a single root module, and 3) examine effect of biochar amendments.

The Potential of Pigeonpea (Cajanus cajan) for Producing Important Components of Renewable Energy and Agricultural Products

NASA Astrophysics Data System (ADS)

Gwata, E.

2012-04-01

In agricultural systems, sustainable crop production is critical in meeting both environmental requirements and the limitations of drought imposed by the effects of global warming. The inputs for crop production and end use of the products should determine the choice of a crop particularly in environments prone to droughts. The objective of this paper is to highlight why a multi-purpose grain legume such as pigeonpea is an ideal crop that can be utilized for producing renewable energy. Firstly, it is highly tolerant to drought and does not require additional soil moisture after the seedling growth stage. The deep tape root extracts moisture and nutrients from deep layers of the soil concomitantly allowing for efficient nutrient recycling. The piscidic acid which is exuded from the roots enhances the solubilization of phosphorus in order to make it available for plant uptake. Secondly, the grain of pigeonpea is suitable for both human food and feedstocks. The grain is rich in oil, vitamins, minerals and protein. The grain can also be used for producing biofuel. In many countries particularly in the developing world, the stover is used as fuel wood or building (roofing) material, thus alleviating pressure on forest products. The crop is grown without the application of inorganic fertilizers as it can fix atmospheric nitrogen symbiotically in its root nodules. Pigeonpea is also ratoonable, producing two or more harvests per season. In addition, it is grown in mixed cropping systems thus optimizing land use. In these regards, pigeonpea is sustainable and environmentally friendly choice for agricultural production of food and energy balance.

Dominant Groups of Potentially Active Bacteria Shared by Barley Seeds become Less Abundant in Root Associated Microbiome

PubMed Central

Yang, Luhua; Danzberger, Jasmin; Schöler, Anne; Schröder, Peter; Schloter, Michael; Radl, Viviane

2017-01-01

Endophytes are microorganisms colonizing plant internal tissues. They are ubiquitously associated with plants and play an important role in plant growth and health. In this work, we grew five modern cultivars of barley in axenic systems using sterile sand mixture as well as in greenhouse with natural soil. We characterized the potentially active microbial communities associated with seeds and roots using rRNA based amplicon sequencing. The seeds of the different cultivars share a great part of their microbiome, as we observed a predominance of a few bacterial OTUs assigned to Phyllobacterium, Paenibacillus, and Trabusiella. Seed endophytes, particularly members of the Enterobacteriacea and Paenibacillaceae, were important members of root endophytes in axenic systems, where there were no external microbes. However, when plants were grown in soil, seed endophytes became less abundant in root associated microbiome. We observed a clear enrichment of Actinobacteriacea and Rhizobiaceae, indicating a strong influence of the soil bacterial communities on the composition of the root microbiome. Two OTUs assigned to Phyllobacteriaceae were found in all seeds and root samples growing in soil, indicating a relationship between seed-borne and root associated microbiome in barley. Even though the role of endophytic bacteria remains to be clarified, it is known that many members of the genera detected in our study produce phytohormones, shape seedling exudate profile and may play an important role in germination and establishment of the seedlings. PMID:28663753

Dominant Groups of Potentially Active Bacteria Shared by Barley Seeds become Less Abundant in Root Associated Microbiome.

PubMed

Yang, Luhua; Danzberger, Jasmin; Schöler, Anne; Schröder, Peter; Schloter, Michael; Radl, Viviane

2017-01-01

Endophytes are microorganisms colonizing plant internal tissues. They are ubiquitously associated with plants and play an important role in plant growth and health. In this work, we grew five modern cultivars of barley in axenic systems using sterile sand mixture as well as in greenhouse with natural soil. We characterized the potentially active microbial communities associated with seeds and roots using rRNA based amplicon sequencing. The seeds of the different cultivars share a great part of their microbiome, as we observed a predominance of a few bacterial OTUs assigned to Phyllobacterium , Paenibacillus , and Trabusiella . Seed endophytes, particularly members of the Enterobacteriacea and Paenibacillaceae, were important members of root endophytes in axenic systems, where there were no external microbes. However, when plants were grown in soil, seed endophytes became less abundant in root associated microbiome. We observed a clear enrichment of Actinobacteriacea and Rhizobiaceae, indicating a strong influence of the soil bacterial communities on the composition of the root microbiome. Two OTUs assigned to Phyllobacteriaceae were found in all seeds and root samples growing in soil, indicating a relationship between seed-borne and root associated microbiome in barley. Even though the role of endophytic bacteria remains to be clarified, it is known that many members of the genera detected in our study produce phytohormones, shape seedling exudate profile and may play an important role in germination and establishment of the seedlings.

Disentangling who is who during rhizosphere acidification in root interactions: combining fluorescence with optode techniques

PubMed Central

Faget, Marc; Blossfeld, Stephan; von Gillhaussen, Philipp; Schurr, Ulrich; Temperton, Vicky M.

2013-01-01

Plant–soil interactions can strongly influence root growth in plants. There is now increasing evidence that root–root interactions can also influence root growth, affecting architecture and root traits such as lateral root formation. Both when species grow alone or in interaction with others, root systems are in turn affected by as well as affect rhizosphere pH. Changes in soil pH have knock-on effects on nutrient availability. A limitation until recently has been the inability to assign species identity to different roots in soil. Combining the planar optode technique with fluorescent plants enables us to distinguish between plant species grown in natural soil and in parallel study pH dynamics in a non-invasive way at the same region of interest (ROI). We measured pH in the rhizosphere of maize and bean in rhizotrons in a climate chamber, with ROIs on roots in proximity to the roots of the other species as well as not-close to the other species. We found clear dynamic changes of pH over time and differences between the two species in rhizosphere acidification. Interestingly, when roots of the two species were interacting, the degree of acidification or alkalization compared to bulk soil was less strong then when roots were not growing in the vicinity of the other species. This cutting-edge approach can help provide a better understanding of plant–plant and plant–soil interactions. PMID:24137168

[Difference of root anatomy characteristics and its effect on DEHP accumulation in two genotypes of Brassica parachinensis].

PubMed

Zeng, Qiao-yun; Mo, Ce-hui; Wen, Rong-lian; Cai, Quan-ying

2010-08-01

Two genotypes of Brassica parachinensis, DEHP high-accumulation of Youqing-60 and low-accumulation of Teqing-60, were grown in hydroponic systems contaminated with DEHP (20 and 50 mg x L(-1)). Anatomy of roots was measured, and their effects on uptake of DEHP in roots and shoots were discussed. The results showed that roots anatomy of two genotypes of Brassica parachinensis and their responds to DEHP pollution were significantly different. DEHP contents in roots and shoots of Youqing-60 were mainly affected by the thickness of cambium in taproot and the diameter of vascular bundle, the coefficients on DEHP of roots and shoots were 0.900 and 0.809, respectively. DEHP contents of Teqing-60 were mainly affected by the thickness of cambium in taproot and cortex in fibre root in roots, which the coefficient was 0.757, and were mainly affected by the thickness of cambium in taproot in shoots, which the coefficient was 0.856. The wood ray cells in roots of Youqing-60 were rectangular shape and arranged orderly. The thickness of cork layer in taproot and cortex in fibre root of Youqing-60 were lower and the quantity of trachea and diameter of vascular bundle and trachea in fibre root of Yonqing-60 were higher than that of Teqing-60, which indicated that DEHP in soil solution and adsorbed on root were easier penetrated into xylem and transported in Youqing-60 than in Teqing-60.

Metaphor, Paradigm, and Education

ERIC Educational Resources Information Center

Ivie, Stanley D.

2017-01-01

Metaphor is a critical tool for thought. Lying at the heart of every systematic body of knowledge are three root metaphors--mechanism, organism, and mind. Historically, schools of philosophy--realism, naturalism, and idealism--have grown up around these metaphors. The root metaphors and their corresponding philosophies provide the paradigms…

Root uptake and translocation of perfluorinated alkyl acids by three hydroponically grown crops.

PubMed

Felizeter, Sebastian; McLachlan, Michael S; De Voogt, Pim

2014-04-16

Tomato, cabbage, and zucchini plants were grown hydroponically in a greenhouse. They were exposed to 14 perfluorinated alkyl acids (PFAAs) at four different concentrations via the nutrient solution. At maturity the plants were harvested, and the roots, stems, leaves, twigs (where applicable), and edible parts (tomatoes, cabbage head, zucchinis) were analyzed separately. Uptake and transfer factors were calculated for all plant parts to assess PFAA translocation and distribution within the plants. Root concentration factors were highest for long-chain PFAAs (>C11) in all three plant species, but these chemicals were not found in the edible parts. All other PFAAs were present in all above-ground plant parts, with transpiration stream concentration factors (TSCFs) of 0.05-0.25. These PFAAs are taken up with the transpiration stream and accumulate primarily in the leaves. Although some systematic differences were observed, overall their uptake from nutrient solution to roots and their further distribution within the plants were similar between plant species and among PFAAs.

Location of Heterodera glycines-induced Syncytia in Soybean as Affected by Soil Water Regimes

PubMed Central

Johnson, A. B.; Kim, K. S.; Riggs, R. D.; Scott, H. D.

1993-01-01

Locations of syncytia induced by the soybean cyst nematode (SCN), Heterodera glycines race 3, were compared in roots of 'Essex', a susceptible soybean (Glycine max (L.) Merr.) cultivar, at three soil water regimes. The plants were grown in wet (-5 to -20 kPa), moderately wet (-30 to -50 kPa), and moderately dry (-60 to -80kPa) autoclaved Captina silt loam soil (Typic Fragiudult). In the moderately dry soil, syncytia were found only in the stele, but in moderately wet and wet soils, syncytia occurred primarily in the cortex and occasionally in the stele. The location of syncytia in the cortical tissue of roots growing in wet and moderately wet soils may account for the tolerance of susceptible soybean cultivars grown under well-irrigated conditions where there is less interference with water transport through roots. Cell-wall perforations and dense cytoplasm were characteristic of syncytial cells observed in root tissues of all treatments. PMID:19279789

Perfluoroalkyl acid distribution in various plant compartments ...

EPA Pesticide Factsheets

Crop uptake of perfluoroalkyl acids (PFAAs) from biosolids-amended soil has been identified as a potential pathway for PFAA entry into the terrestrial food chain. This study compared the uptake of PFAAs in greenhouse-grown radish (Raphanus sativus), celery (Apium graveolens var.dulce), tomato (Lycopersicon lycopersicum), and sugar snap pea (Pisum sativum var. macrocarpon) from an industrially impacted biosolids-amended soil, a municipal biosolids­ amended soil, and a control soil. Individual concentrations of PFAAs, on a dry weight basis, in mature, edible portions of crops grown in soil amended with PFAA industrially impacted biosolids were highest for perfluorooctanoate (PFOA; 67 ng/g) in radish root, perfluorobutanoate (PFBA;232 ng/g) in celery shoot, and PFBA (150 ng/g) in pea fruit. Comparatively, PFAA concentrations in edible compartments of crops grown in the municipal biosolids-amended soil and in the control soil were less than 25 ng/g. Bioaccumulation factors (BAFs) were calculated for the root, shoot, and fruit compartments (as applicable) of all crops grown in the industrially impacted soil. BAFs were highest for PFBA in the shoots of all crops, as well as in the fruit compartment of pea. Root­ soil concentration factors (RCFs) for tomato and pea were independent of PFAA chain length, while radish and celery RCFs showed a slight decrease with increasing chain length. Shoot-soil concentration factors (SCFs) for all crops showed a decrease with incre

Multimedia models of human exposure to industrial emissions through food products: Identifying the critical pathways

DOE Office of Scientific and Technical Information (OSTI.GOV)

McKone, T.E.; Maddalena, R.L.; Dowdy, D.L.

1995-12-31

The magnitude of potential human exposure through foods can be and has been assessed through food-product samples. Reducing these exposures requires that measuring not only the exposure media (food) concentrations but also defining the processes that link various contaminant sources to food. The authors present here a general approach for quantifying human exposure to contaminants in home-grown foods using four factors-ambient environmental concentrations in air and soil; bioconcentration factors between air, soil, leaves, and roots; translocations from leaves and roots to edible-plant parts; and human activity patterns associated with consumption of home-grown food products. The authors combined these factors inmore » a general model and used sensitivity analyses to assess the important contributions to the imprecision of exposure estimates. Despite large uncertainties about human activities, they found the major source of uncertainty (variance) in exposure estimates is attributable to imprecision in quantifying bioconcentration. This is especially evident for persistent and fat-soluble compounds--such as PCBs, PAHs, dioxins, and furans. The evaluation of analytical and theoretical methods used to characterize bioconcentration factors reveals that molecular connectivity indices (MCIs) based on molecular structure are better predictors of bioconcentration in plants than are the solubility factors currently in use. The authors describe ongoing laboratory experiments in exposure chambers with garden foods such as leafy vegetables and root crops. They then assess the ability of these methods to better define chemical mass transfers among the components of the home-garden system-air, soil-organic phases, soil solution, plant roots, and plant leaves.« less

Association of Shifting Populations in the Root Zone Microbiome of Millet with Enhanced Crop Productivity in the Sahel Region (Africa)

PubMed Central

Assigbetse, Komi; Bayala, Roger; Chapuis-Lardy, Lydie; Dick, Richard P.; McSpadden Gardener, Brian B.

2015-01-01

This study characterized specific changes in the millet root zone microbiome stimulated by long-term woody-shrub intercropping at different sites in Senegal. At the two study sites, intercropping with woody shrubs and shrub residue resulted in a significant increase in millet [Pennisetum glaucum (L.) R. Br.] yield (P < 0.05) and associated patterns of increased diversity in both bacterial and fungal communities in the root zone of the crop. Across four experiments, operational taxonomic units (OTUs) belonging to Chitinophaga were consistently significantly (P < 0.001) enriched in the intercropped samples, and “Candidatus Koribacter” was consistently significantly enriched in samples where millet was grown alone. Those OTUs belonging to Chitinophaga were enriched more than 30-fold in residue-amended samples and formed a distinct subgroup from all OTUs detected in the genus. Additionally, OTUs belonging to 8 fungal genera (Aspergillus, Coniella, Epicoccum, Fusarium, Gibberella, Lasiodiplodia, Penicillium, and Phoma) were significantly (P < 0.005) enriched in all experiments at all sites in intercropped samples. The OTUs of four genera (Epicoccum, Fusarium, Gibberella, and Haematonectria) were consistently enriched at sites where millet was grown alone. Those enriched OTUs in intercropped samples showed consistently large-magnitude differences, ranging from 30- to 1,000-fold increases in abundance. Consistently enriched OTUs in intercropped samples in the genera Aspergillus, Fusarium, and Penicillium also formed phylogenetically distinct subgroups. These results suggest that the intercropping system used here can influence the recruitment of potentially beneficial microorganisms to the root zone of millet and aid subsistence farmers in producing higher-yielding crops. PMID:25681183

Phytophthora tentaculata

Treesearch

Suzanne Rooney-Latham; Cheryl Blomquist; Ted Swiecki; Elizabeth Bernhardt

2015-01-01

Phytophthora tentaculata Kröber & Marwitz was described in 1993 in Germany on greenhouse-grown nursery ornamentals. It has since been found in Italy, Spain, China and the U.S. (California) causing a root and stem rot of many different plant species including nursery-grown native species used for habitat restoration. P. tentaculata...

A comparison of root iron uptake rates in Carya aquatica and Carya illinoinensis

USDA-ARS?s Scientific Manuscript database

Carya aquatica (water hickory) thrives in water saturated soils, where ferrous iron predominates. However, this species exhibits iron deficiency when grown in drier soils. Carya illinoinensis (pecan) is generally iron-adequate when grown in non-flooded areas, where iron is found predominantly in the...

A comparison of root iron acquisition capabilities in Carya aquatica and Carya illinoinensis

USDA-ARS?s Scientific Manuscript database

Carya aquatica (water hickory) thrives in water-saturated soils where ferrous iron is prevalent. However, when grown in drier soils, this species exhibits iron deficiency. Carya illinoinensis (pecan), a closely related species to Carya aquatica, is generally iron-adequate when grown in non-flooded ...

Evaluation of Wild Lentil Species as Genetic Resources to Improve Drought Tolerance in Cultivated Lentil.

PubMed

Gorim, Linda Y; Vandenberg, Albert

2017-01-01

Increasingly unpredictable annual rainfall amounts and distribution patterns have far reaching implications for pulse crop biology. Seedling and whole plant survival will be affected given that water is a key factor in plant photosynthesis and also influences the evolving disease spectrum that affects crops. The wild relatives of cultivated lentil are native to drought prone areas, making them good candidates for the evaluation of drought tolerance traits. We evaluated root and shoot traits of genotypes of cultivated lentil and five wild species grown under two water deficit regimes as well as fully watered conditions over a 13 week period indoors. Plants were grown in sectioned polyvinyl chloride (PVC) tubes containing field soil from the A, B, and C horizons. We found that root distribution into different soil horizons varied among wild lentil genotypes. Secondly, wild lentil genotypes employed diverse strategies such as delayed flowering, reduced transpiration rates, reduced plant height, and deep root systems to either escape, evade or tolerate drought conditions. In some cases, more than one drought strategy was observed within the same genotype. Sequence based classification of wild and cultivated genotypes did not explain patterns of drought response. The environmental conditions at their centers of origin may explain the patterns of drought strategies observed in wild lentils. The production of numerous small seeds by wild lentil genotypes may have implications for yield improvement in lentil breeding programs.

Root biomass, turnover and net primary productivity of a coffee agroforestry system in Costa Rica: effects of soil depth, shade trees, distance to row and coffee age.

PubMed

Defrenet, Elsa; Roupsard, Olivier; Van den Meersche, Karel; Charbonnier, Fabien; Pastor Pérez-Molina, Junior; Khac, Emmanuelle; Prieto, Iván; Stokes, Alexia; Roumet, Catherine; Rapidel, Bruno; de Melo Virginio Filho, Elias; Vargas, Victor J; Robelo, Diego; Barquero, Alejandra; Jourdan, Christophe

2016-08-21

In Costa Rica, coffee (Coffea arabica) plants are often grown in agroforests. However, it is not known if shade-inducing trees reduce coffee plant biomass through root competition, and hence alter overall net primary productivity (NPP). We estimated biomass and NPP at the stand level, taking into account deep roots and the position of plants with regard to trees. Stem growth and root biomass, turnover and decomposition were measured in mixed coffee/tree (Erythrina poeppigiana) plantations. Growth ring width and number at the stem base were estimated along with stem basal area on a range of plant sizes. Root biomass and fine root density were measured in trenches to a depth of 4 m. To take into account the below-ground heterogeneity of the agroforestry system, fine root turnover was measured by sequential soil coring (to a depth of 30 cm) over 1 year and at different locations (in full sun or under trees and in rows/inter-rows). Allometric relationships were used to calculate NPP of perennial components, which was then scaled up to the stand level. Annual ring width at the stem base increased up to 2·5 mm yr -1 with plant age (over a 44-year period). Nearly all (92 %) coffee root biomass was located in the top 1·5 m, and only 8 % from 1·5 m to a depth of 4 m. Perennial woody root biomass was 16 t ha -1 and NPP of perennial roots was 1·3 t ha -1 yr -1 Fine root biomass (0-30 cm) was two-fold higher in the row compared with between rows. Fine root biomass was 2·29 t ha -1 (12 % of total root biomass) and NPP of fine roots was 2·96 t ha -1 yr -1 (69 % of total root NPP). Fine root turnover was 1·3 yr -1 and lifespan was 0·8 years. Coffee root systems comprised 49 % of the total plant biomass; such a high ratio is possibly a consequence of shoot pruning. There was no significant effect of trees on coffee fine root biomass, suggesting that coffee root systems are very competitive in the topsoil. © The Author 2016. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

[Some peculiar features of liquid supply to the root medium of plants growing in microgravity

NASA Technical Reports Server (NTRS)

Podol'skii, I. G.; Sychev, V. N.; Levinskikh, M. A.; Strugov, O. M.; Bingham, G. E.; Salisbury, F. B. (Principal Investigator)

1998-01-01

Sixteen point probes monitored moisture level in the root medium of the wheat plants grown in greenhouse SVET on the MIR/NASA space science program. The article outlines types of water migration in the absence of gravity. Hydrophysical characteristics of perspective root media have been explored. Results of the water supply monitoring and control in the course of experiment are reported. The authors put forward porous root media to facilitate water migration and aeration.

Examining Dehydration and Hypoxic Stress in Wheat Plants Using a Porous Tube Plant Nutrient Delivery System Developed for Microgravity

NASA Technical Reports Server (NTRS)

Dreschel, T. W.; Hall, C. R.; Foster, T. E.; Salganic, M.; Warren, L.; Corbett, M.

2005-01-01

The Porous Tube Plant Nutrient Delivery System (PTPNDS) was designed for NASA to grow plants in microgravity of space. The system utilizes a controlled fluid loop to supply nutrients and water to plant roots growing on a ceramic surface moistened by capiflary action. A PTPNDS test bed was developed and utilizing remote sensing systems, spectral analyses procedures, gas-exchange, and fluorescence measurements, we examined differences in plant water status for wheat plants (Triticum aestivum, cv. Perigee) grown in a modified growth chamber during the summers of 2003 and 2004. Some differences in plant performance were detectable in the gas-exchange and fluorescence measurements. For instance, in both years the plants grown with the most available water had the lowest rates of photosynthesis and exhibited higher proportions of non-photochemical quenching particularly under low light levels. In addition, small differences in mean leaf water content between treatments were detected using spectral reflectance analyses.

Copper-Treated Containers Influence Root Development of Longleaf Pine Seedlings

Treesearch

James P. Barnett; John M. McGilvray

2002-01-01

Development of longleaf pine (Pinus palustris Mill.) seedlings grown in CopperblockTM containers and BC/ CFC First ChoiceTM Styrofoam blocks, with applications of Spin Out® root growth regulator, were compared to control seedlings. The copper treatments significantly changed seedling morphology; at...

Auxin-enhanced root growth for phytoremediation of sewage-sludge amended soil.

PubMed

Liphadzi, M S; Kirkham, M B; Paulsen, G M

2006-06-01

A technology to increase root growth would be advantageous for phytoremediation of trace metal polluted soil, because more roots would be available for metal uptake. The objective of this study was to determine if the auxin, indole-3-acetic acid (IAA), would increase root growth in soil with metals from sewage sludge, when the tetrasodium salt of the chelate EDTA (ethylenediamine-tetraacetic acid) was added to solubilize the metals. Sunflower (Helianthus annuus L.) plants grew in large pots containing either soil from a sludge farm or composted sludge. The EDTA salt was added at a rate of 1 g kg(-1) soil 37 days after planting. IAA at the rate of 3 or 6 mg l(-1) was sprayed on the leaves (500 ml) and added to the soil (500 ml) three times: 41, 50, and 74 days after planting. At harvest 98 days after planting, oven-dry weights were measured, and plant organs were analyzed for Cd, Cu, Fe, Mn, Ni, Pb, and Zn. Metal uptake was determined as the product of metal concentration in an organ and weight. IAA increased root growth of plants grown in the soil with sludge when no EDTA was present. With no EDTA, Mn and Ni in leaves of plants grown in the soil were higher at 3 and 6 mg l(-1) IAA compared to 0 mg l(-1) IAA. With and without EDTA, Cd and Pb in leaves of plants grown in the compost were higher with 3 and 6 mg l(-1) IAA compared to 0 mg l(-1) IAA.

Lead levels of edibles grown in contaminated residential soils: a field survey.

PubMed

Finster, Mary E; Gray, Kimberly A; Binns, Helen J

2004-03-29

Plants grown in lead contaminated soils can accumulate lead from the adherence of dust and translocation into the plant tissue. In order to evaluate the potential health hazard due to the consumption of plants grown in residential gardens contaminated by lead, a survey of the lead concentrations in a typical array of edible vegetables, fruits and herbs was conducted. Samples of garden plants harvested from the field were washed with detergent or water alone to remove adhered soil. They were dried, separated into sections including root, shoot and edible fruit, and then analyzed for lead content using inductively coupled plasma-atomic emission spectrometry (ICP-AES). Soil samples, taken in conjunction with the plant harvesting, were analyzed using flame atomic absorbance (FAA). A pattern of lead transference from soil through the root to the stem and leaves of garden crops was found. The majority of the lead was concentrated in the roots (root:soil ranging from 0.02 to 0.51), with some translocation into the shoots (shoot:soil as high as 0.10). This pattern is a concern particularly for crops in which the root, stems, stalks or leaves are edible. The lead concentration in fruiting vegetables was less than the detection limit of 10 ppm (microgram lead/gram dry plant matter). Some edible portions of the leafy vegetables and herbs, however, were found to have lead levels that, if consumed, could contribute to the total body burden of lead. Therefore, urban gardeners should test the lead levels in their soils and develop strategies to ensure safety.

Root-type-specific plasticity in response to localized high nitrate supply in maize (Zea mays).

PubMed

Yu, Peng; Hochholdinger, Frank; Li, Chunjian

2015-10-01

Shoot-borne roots contribute to most of the nutrient uptake throughout the life cycle of maize (Zea mays). Compared with numerous studies with embryonic roots, detailed information on the phenotypic plasticity of shoot-borne roots in response to a heterogeneous nitrogen supply is scarce. The present study therefore provides a comprehensive profile of fine-scale plastic responses of distinct root types to localized high nitrate supply. Seedlings of the maize inbred line B73 were grown in split-root systems. The anatomy and morphological plasticity of the primary root and the roots initiated from the 2nd, 5th and 7th shoot nodes, and their lateral roots, were studied in response to local high nitrate supply to one side of the root system. In contrast to the insensitivity of axial roots, local high nitrate supply increased the length of 1st-order lateral roots on the primary root and the three whorls of shoot-borne roots at different growth stages, and increased the density of 1st-order lateral roots on the 7th shoot-borne root after silking. The length and density of 2nd-order lateral roots on the three whorls of shoot-borne roots displayed a more flexible response to local high nitrate than 1st-order lateral roots. Root diameter and number, and total area and diameter of metaxylem vessels increased from the primary root to early and then later developed shoot-borne roots, which showed a positive relationship with shoot growth and N accumulation. Maize axial roots and lateral roots responded differently to local high nitrate, and this was related to their function. The extent of morphological plasticity of lateral roots in response to local high nitrate depended on the initiation time of the shoot-borne roots on which the lateral roots developed. Morphological plasticity was higher on 2nd-order than on 1st-order lateral roots. The results suggest that higher order lateral root branching might be a potential target for genetic improvement in future maize breeding. © The Author 2015. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Comparison of two possible routes of pathogen contamination of spinach leaves in a hydroponic cultivation system.

PubMed

Koseki, Shigenobu; Mizuno, Yasuko; Yamamoto, Kazutaka

2011-09-01

The route of pathogen contamination (from roots versus from leaves) of spinach leaves was investigated with a hydroponic cultivation system. Three major bacterial pathogens, Escherichia coli O157:H7, Salmonella, and Listeria monocytogenes, were inoculated into the hydroponic solution, in which the spinach was grown to give concentrations of 10⁶ and 10³ CFU/ml. In parallel, the pathogens were inoculated onto the growing leaf surface by pipetting, to give concentrations of 10⁶ and 10³ CFU per leaf. Although contamination was observed at a high rate through the root system by the higher inoculum (10⁶ CFU) for all the pathogens tested, the contamination was rare when the lower inoculum (10³ CFU) was applied. In contrast, contamination through the leaf occurred at a very low rate, even when the inoculum level was high. For all the pathogens tested in the present study, the probability of contamination was promoted through the roots and with higher inoculum levels. The probability of contamination was analyzed with logistic regression. The logistic regression model showed that the odds ratio of contamination from the roots versus from the leaves was 6.93, which suggested that the risk of contamination from the roots was 6.93 times higher than the risk of contamination from the leaves. In addition, the risk of contamination by L. monocytogenes was about 0.3 times that of Salmonella enterica subsp. enterica serovars Typhimurium and Enteritidis and E. coli O157:H7. The results of the present study indicate that the principal route of pathogen contamination of growing spinach leaves in a hydroponic system is from the plant's roots, rather than from leaf contamination itself.

Comparative response of six grapevine rootstocks to inoculation with arbuscular mycorrhizal fungi based on root traits

NASA Astrophysics Data System (ADS)

Pogiatzis, Antreas; Bowen, Pat; Hart, Miranda; Holland, Taylor; Klironomos, John

2017-04-01

Arbuscular mycorrhizal (AM) symbiosis has been proven to be essential in grapevines, sustaining plant growth especially under abiotic and biotic stressors. The mycorrhizal growth response of young grapevines varies among rootstock cultivars and the underlying mechanisms involved in this variation are unknown. We predicted that this variation in mycorrhizal response may be explained by differences in root traits among rootstocks. We analyzed the entire root system of six greenhouse-grown rootstocks (Salt Creek, 3309 Couderc, Riparia Gloire, 101-14 Millardet et de Grasset, Swarzmann, Teleki 5C), with and without AM fungal inoculation (Rhizophagus irregularis) and characterized their morphological and architectural responses. Twenty weeks after the inoculation, aboveground growth was enhanced by AM colonization. The rootstock varieties were distinctly different in their response to AM fungi, with Salt Creek receiving the highest growth benefit, while Schwarzmann and 5C Teleki receiving the lowest. Plant responsiveness to AM fungi was negatively correlated with branching intensity (fine roots per root length). Furthermore, there was evidence that mycorrhizas can influence the expression of root traits, inducing a higher branching intensity and a lower root to shoot ratio. The results of this study will help to elucidate how interactions between grapevine rootstocks and AM fungi may benefit the establishment of new vineyards.

Endophytic Herbaspirillum seropedicae expresses nif genes in gramineous plants.

PubMed

Roncato-Maccari, Lauren D B; Ramos, Humberto J O; Pedrosa, Fabio O; Alquini, Yedo; Chubatsu, Leda S; Yates, Marshall G; Rigo, Liu U; Steffens, Maria Berenice R; Souza, Emanuel M

2003-07-01

Abstract The interactions between maize, sorghum, wheat and rice plants and Herbaspirillum seropedicae were examined microscopically following inoculation with the H. seropedicae LR15 strain, a Nif(+) (Pnif::gusA) mutant obtained by the insertion of a gusA-kanamycin cassette into the nifH gene of the H. seropedicae wild-type strain. The expression of the Pnif::gusA fusion was followed during the association of the diazotroph with the gramineous species. Histochemical analysis of seedlings of maize, sorghum, wheat and rice grown in vermiculite showed that strain LR15 colonized root surfaces and inner tissues. In early steps of the endophytic association, H. seropedicae colonized root exudation sites, such as axils of secondary roots and intercellular spaces of the root cortex; it then occupied the vascular tissue and there expressed nif genes. The expression of nif genes occurred in roots, stems and leaves as detected by the GUS reporter system. The expression of nif genes was also observed in bacterial colonies located in the external mucilaginous root material, 8 days after inoculation. Moreover, the colonization of plant tissue by H. seropedicae did not depend on the nitrogen-fixing ability, since similar numbers of cells were isolated from roots or shoots of the plants inoculated with Nif(+) or Nif(-) strains.

Response of “Alamo” switchgrass tissue chemistry and biomass to nitrogen fertilization in West Tennessee, USA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garten, Charles T.; Brice, Deanne J.; Castro, Hector F.

2011-01-01

Switchgrass (Panicum virgatum) is a perennial, warm-season grass that has been identified as a potential biofuel feedstock over a large part of North America. We examined above- and belowground responses to nitrogen fertilization in “Alamo” switchgrass grown in West Tennessee, USA. The fertilizer study included a spring and fall sampling of 5-year old switchgrass grown under annual applications of 0, 67, and 202 kg N ha -1 (as ammonium nitrate). Fertilization changed switchgrass biomass allocation as indicated by root:shoot ratios. End-of-growing season root:shoot ratios (mean ± SE) declined significantly (P ≤ 0.05) at the highest fertilizer nitrogen treatment (2.16 ±more » 0.08, 2.02 ± 0.18, and 0.88 ± 0.14, respectively, at 0, 67, and 202 kg N ha -1). Fertilization also significantly increased above- and belowground nitrogen concentrations and decreased plant C:N ratios. Data are presented for coarse live roots, fine live roots, coarse dead roots, fine dead roots, and rhizomes. At the end of the growing season, there was more carbon and nitrogen stored in belowground biomass than aboveground biomass. Finally, fertilization impacted switchgrass tissue chemistry and biomass allocation in ways that potentially impact soil carbon cycle processes and soil carbon storage.« less

Compositional shifts in root-associated bacterial and archaeal microbiota track the plant life cycle in field-grown rice

PubMed Central

Edwards, Joseph A.; Santos-Medellín, Christian M.; Liechty, Zachary S.; Nguyen, Bao; Lurie, Eugene; Eason, Shane; Phillips, Gregory

2018-01-01

Bacterial communities associated with roots impact the health and nutrition of the host plant. The dynamics of these microbial assemblies over the plant life cycle are, however, not well understood. Here, we use dense temporal sampling of 1,510 samples from root spatial compartments to characterize the bacterial and archaeal components of the root-associated microbiota of field grown rice (Oryza sativa) over the course of 3 consecutive growing seasons, as well as 2 sites in diverse geographic regions. The root microbiota was found to be highly dynamic during the vegetative phase of plant growth and then stabilized compositionally for the remainder of the life cycle. Bacterial and archaeal taxa conserved between field sites were defined as predictive features of rice plant age by modeling using a random forest approach. The age-prediction models revealed that drought-stressed plants have developmentally immature microbiota compared to unstressed plants. Further, by using genotypes with varying developmental rates, we show that shifts in the microbiome are correlated with rates of developmental transitions rather than age alone, such that different microbiota compositions reflect juvenile and adult life stages. These results suggest a model for successional dynamics of the root-associated microbiota over the plant life cycle. PMID:29474469

Compositional shifts in root-associated bacterial and archaeal microbiota track the plant life cycle in field-grown rice.

PubMed

Edwards, Joseph A; Santos-Medellín, Christian M; Liechty, Zachary S; Nguyen, Bao; Lurie, Eugene; Eason, Shane; Phillips, Gregory; Sundaresan, Venkatesan

2018-02-01

Bacterial communities associated with roots impact the health and nutrition of the host plant. The dynamics of these microbial assemblies over the plant life cycle are, however, not well understood. Here, we use dense temporal sampling of 1,510 samples from root spatial compartments to characterize the bacterial and archaeal components of the root-associated microbiota of field grown rice (Oryza sativa) over the course of 3 consecutive growing seasons, as well as 2 sites in diverse geographic regions. The root microbiota was found to be highly dynamic during the vegetative phase of plant growth and then stabilized compositionally for the remainder of the life cycle. Bacterial and archaeal taxa conserved between field sites were defined as predictive features of rice plant age by modeling using a random forest approach. The age-prediction models revealed that drought-stressed plants have developmentally immature microbiota compared to unstressed plants. Further, by using genotypes with varying developmental rates, we show that shifts in the microbiome are correlated with rates of developmental transitions rather than age alone, such that different microbiota compositions reflect juvenile and adult life stages. These results suggest a model for successional dynamics of the root-associated microbiota over the plant life cycle.

Induced Phytoextraction of Lead Through Chemical Manipulation of Switchgrass and Corn; Role of Iron Supplement.

PubMed

Johnson, Deayne M; Deocampo, Daniel M; El-Mayas, Hanan; Greipsson, Sigurdur

2015-01-01

The effects of combined chemical application of benomyl, ethylenedianinetetraacetate (EDTA), and iron (Fe) (foliar and root) on lead (Pb) phytoextraction by switchgrass (Panicum virgatum) and corn (Zea mays) was examined. Switchgrass was grown in Pb-contaminated urban topsoil with the following treatments: (C) Control, (B) benomyl, (E) EDTA, (F) foliar-Fe, (BE) benomyl + EDTA, (BF) benomyl + foliar-Fe, (FE) foliar-Fe + EDTA, (BFE) benomyl + foliar-Fe + EDTA. Corn was grown in sand-culture supplemented with Pb (500 mg kg(-1)) with the following treatments: (C) control, (B) benomyl, (E) EDTA, (F) root-Fe, (BE) benomyl + EDTA, (BF) benomyl + root-Fe, (FE) root-iron + EDTA, and, (BFE) benomyl + root-Fe + EDTA. All treatments were replicated three times and pots were arranged in a completely randomized design. Plants were analyzed for element concentration (Fe, Zn, P, and Pb) using either inductively coupled plasma (argon) atomic emission spectroscopy (ICP-AES) or graphite furnace atomic absorption spectrometer. Iron supplementation (foliar and root) affected Pb-translocation in plants. Foliar-Fe treatment increased translocation ratio of Pb (TF-Pb) significantly compared to other treatments with the exception of plants treated with benomyl and BF. Root-Fe treatment in combination with EDTA (FE) increased TF-Pb significantly compared to other treatments. Phytoextraction was improved by the combined chemical application; plants treated with BFE treatment increased Pb-total-phytoextraction by 424% compared to Control plants.

Contrasting physiological effects of partial root zone drying in field-grown grapevine (Vitis vinifera L. cv. Monastrell) according to total soil water availability

PubMed Central

Romero, Pascual; Dodd, Ian C.; Martinez-Cutillas, Adrian

2012-01-01

Different spatial distributions of soil moisture were imposed on field-grown grapevines by applying the same irrigation volumes to the entire (DI; deficit irrigation) or part of the (PRD; partial root zone drying) root zone. Five treatments were applied: controls irrigated at 60% ETc (crop evapotranspiration) for the whole season (308 mm year−1); DI-1 and PRD-1 that received the same irrigation as controls before fruit set, 30% ETc from fruit set to harvest and 45% ETc post-harvest (192 mm year−1); and DI-2 and PRD-2 that were the same, except that 15% ETc was applied from fruit set to harvest (142 mm year−1). Compared with DI-1, PRD-1 maintained higher leaf area post-veraison and increased root water uptake, whole-plant hydraulic conductance, leaf transpiration, stomatal conductance, and photosynthesis, but decreased intrinsic gas exchange efficiency without causing differences in leaf xylem abscisic acid (ABA) concentration. Compared with DI-2, PRD-2 increased leaf xylem ABA concentration and decreased root water uptake, whole-plant hydraulic conductance, leaf transpiration, stomatal conductance, and photosynthesis, mainly at the beginning of PRD cycles. Distinctive PRD effects (e.g. greater stomatal closure) depended on the volumetric soil water content of the wet root zone, as predicted from a model of root-to-shoot ABA signalling. PMID:22451721

[Differences in growth and ontogenetic development of plants grown in the Earth gravitational field in the natural and inverse orientation].

PubMed

Smolianina, S O; Berkovich, Iu A; Krivobok, N M; Ivanov, V B

2003-01-01

Wheat plants Triticum aestivum L., Apogee cultivar, were grown in the natural and inverse orientation of the Earth gravitational field. Special vegetation containers with double bottom were used for the cultivation. The upper bottom made of porous titanium served as a hydrophilic porous membrane stabilizing aquatic potential in the root-inhabited zone at a given level. Normal plants yielding viable seeds were obtained for both natural and inverse orientation. In our experiments, the inverse orientation induced dry weight accumulation by the plants as well as development of productive tillering shoots and increased the shoot-root dry weight ratio.

Plant responses to elevated atmospheric CO/sub 2/ with emphasis on belowground processes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Norby, R.J.; Luxmoore, R.J.; O'Neill, E.G.

1984-12-01

Consideration of the interrelationships between carbon, water, and nutrient pathways in soil-plant systems has led to the hypothesis that stimulation of root and rhizosphere processes by elevated levels of CO/sub 2/ will increase nutrient availability and lead to an increase in plant growth. Several experiments were conducted to investigate the effects of CO/sub 2/ concentration on carbon allocation, root exudation, nitrogen utilization, and microbial responses, as well as overall plant growth and nutrient utilization. Increases in the growth of yellow-poplar (Liriodendron tulipifera L.) seedlings in response to elevated CO/sub 2/ were demonstrated even when the plants were under apparent nutrientmore » limitation in a forest soil. The proportion of photosynthetically fixed carbon that was allocated to the roots of yellow-poplar and hazel alder (Alnus serrulata (Ait.) Willd.) seedlings was greater at 700 ppM CO/sub 2/ than at ambient CO/sub 2/. Exudation of carbon from yellow-poplar roots also tended to be higher in elevated CO/sub 2/. Responses of rhizosphere microbial populations to elevated CO/sub 2/ were inconsistent, but there was a trend toward relatively fewer ammonium oxidizers, nitrite oxidizers, and phosphate solubilizers in the rhizosphere population of yellow-poplar seedlings grown in 700 ppM CO/sub 2/ compared to that of seedlings grown in ambient CO/sub 2/. Other observed trends included increased nodulation and nitrogenase activity and decreased nitrate reductase activity in hazel alder seedlings in elevated CO/sub 2/. Net uptake of some essential plant nutrients, aluminum, and other trace metals by Virginia pine (Pinus virginiana Mill.) increased with increasing CO/sub 2/ concentration. There was less leaching of some nutrients from soil-plant systems with Virginia pine and yellow-poplar seedlings but increased leaching of zinc. 123 references, 16 figures, 17 tables.« less

Heritability of first-order-lateral roots in five Quercus species: effect on 1-0 seedling quality evaluation

Treesearch

Paul P. Kormanik; Shi-Jean S. Sung; Taryn L. Kormanik; Stanley J. Zarnoch; Scott Schlarbaum

1997-01-01

Heritability estimates (h2) were calculated for first-order lateral root (FOLR) numbers on a family plot mean basis for 5 Quercus species: Q. alba, Q. falcata, Q, michauxii, Q. pagoda, and Q. rubra. All species were grown with the...

Regeneration and productivity of aspen grown on repeated short rotations.

Treesearch

Donald A. Perala

1979-01-01

Regeneration and productivity of aspen cannot be sustained on rotations shorter than about 8 years. Productivity losses on short rotations are physiological and morphological rather than nutritional in nature. Stump and root collar sprouts, which are rare in mature stands, were more numerous than root suckers.

Rhizobacterial community structure and function in a dryland agroecosystem

USDA-ARS?s Scientific Manuscript database

We recently discovered large populations of phenazine-producing (Phz+) Pseudomonas strains and concentrations of the antibiotic phenazine-1-carboxylic acid (PCA) of up to 1.6 µg g-1 of root plus rhizosphere soil on roots of non-irrigated cereals grown over more than a million hectares of the Columbi...

Toxicity of Inorganic Mercury to Native Australian Grass Grown in Three Different Soils.

PubMed

Mahbub, Khandaker Rayhan; Kader, Mohammed; Krishnan, Kannan; Labbate, Maurizio; Naidu, Ravi; Megharaj, Mallavarapu

2017-06-01

In this study, three native Australian grasses namely Iseilema membranaceum (Barcoo), Dichanthium sericeum (Queensland Blue) and Sporobolus africanus (Tussock) were grown in three different soils spiked with different concentrations of inorganic mercury and the root elongation was monitored up to 28 days following the germination. Results showed that mercury at certain concentrations significantly inhibited the root growth of all three tested native grasses grown in three soils, however, the toxicity was less in the soil with high organic carbon content and acidic pH. The calculated EC 50 values ranged from 10 to 224 mg/kg total Hg in soil. However, the EC 10 values indicated that existing guideline values for mercury may be of protective to the native Australian vegetation. Considering their tolerance to soil mercury, these grass species have the potential for their use in rehabilitation of mercury contaminated sites.

Development and Validation of a SPME-GC-MS Method for In situ Passive Sampling of Root Volatiles from Glasshouse-Grown Broccoli Plants Undergoing Below-Ground Herbivory by Larvae of Cabbage Root Fly, Delia radicum L.

PubMed

Deasy, William; Shepherd, Tom; Alexander, Colin J; Birch, A Nicholas E; Evans, K Andrew

2016-11-01

Research on plant root chemical ecology has benefited greatly from recent developments in analytical chemistry. Numerous reports document techniques for sampling root volatiles, although only a limited number describe in situ collection. To demonstrate a new method for non-invasive in situ passive sampling using solid phase micro extraction (SPME), from the immediate vicinity of growing roots. SPME fibres inserted into polyfluorotetrafluoroethylene (PTFE) sampling tubes located in situ which were either perforated, covered with stainless steel mesh or with microporous PTFE tubing, were used for non-invasive sub-surface sampling of root volatiles from glasshouse-grown broccoli. Sampling methods were compared with above surface headspace collection using Tenax TA. The roots were either mechanically damaged or infested with Delia radicum larvae. Principal component analysis (PCA) was used to investigate the effect of damage on the composition of volatiles released by broccoli roots. Analyses by gas chromatography-mass spectrometry (GC-MS) with SPME and automated thermal desorption (ATD) confirmed that sulphur compounds, showing characteristic temporal emission patterns, were the principal volatiles released by roots following insect larval damage. Use of SPME with in situ perforated PTFE sampling tubes was the most robust method for out-of-lab sampling. This study describes a new method for non-invasive passive sampling of volatiles in situ from intact and insect damaged roots using SPME. The method is highly suitable for remote sampling and has potential for wide application in chemical ecology/root/soil research. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

De novo assembly and comparative analysis of root transcriptomes from different varieties of Panax ginseng C. A. Meyer grown in different environments.

PubMed

Zhen, Gang; Zhang, Lei; Du, YaNan; Yu, RenBo; Liu, XinMin; Cao, FangRui; Chang, Qi; Deng, XingWang; Xia, Mian; He, Hang

2015-11-01

Panax ginseng C. A. Meyer is an important traditional herb in eastern Asia. It contains ginsenosides, which are primary bioactive compounds with medicinal properties. Although ginseng has been cultivated since at least the Ming dynasty to increase production, cultivated ginseng has lower quantities of ginsenosides and lower disease resistance than ginseng grown under natural conditions. We extracted root RNA from six varieties of fifth-year P. ginseng cultivars representing four different growth conditions, and performed Illumina paired-end sequencing. In total, 163,165,706 raw reads were obtained and used to generate a de novo transcriptome that consisted of 151,763 contigs (76,336 unigenes), of which 100,648 contigs (66.3%) were successfully annotated. Differential expression analysis revealed that most differentially expressed genes (DEGs) were upregulated (246 out of 258, 95.3%) in ginseng grown under natural conditions compared with that grown under artificial conditions. These DEGs were enriched in gene ontology (GO) terms including response to stimuli and localization. In particular, some key ginsenoside biosynthesis-related genes, including HMG-CoA synthase (HMGS), mevalonate kinase (MVK), and squalene epoxidase (SE), were upregulated in wild-grown ginseng. Moreover, a high proportion of disease resistance-related genes were upregulated in wild-grown ginseng. This study is the first transcriptome analysis to compare wild-grown and cultivated ginseng, and identifies genes that may produce higher ginsenoside content and better disease resistance in the wild; these genes may have the potential to improve cultivated ginseng grown in artificial environments.

Responses of seminal wheat seedling roots to soil water deficits.

PubMed

Trejo, Carlos; Else, Mark A; Atkinson, Christopher J

2018-04-01

The aims of this paper are to develop our understanding of the ways by which soil water deficits influence early wheat root growth responses, particularly how seminal roots respond to soil drying and the extent to which information on differences in soil water content are conveyed to the shoot and their impact on shoot behaviour. To achieve this, wheat seedlings have been grown, individually for around 25 days after germination in segmented soil columns within vertical plastic compartments. Roots were exposed to different soil volumetric moisture contents (SVMC) within the two compartments. Experiments where the soil in the lower compartment was allowed to dry to different extents, while the upper was maintained close to field capacity, showed that wheat seedlings allocated proportionally more root dry matter to the lower drier soil compartment. The total production of root, irrespective of the upper or lower SVMC, was similar and there were no detected effects on leaf growth rate or gas exchange. The response of seminal roots to proportionally increase their allocation of dry matter, to the drier soil was unexpected with such plasticity of roots system development traditionally linked to heterogeneous nutrient distribution than accessing soil water. In experiments where the upper soil compartment was allowed to dry, root growth slowed and leaf growth and gas exchange declined. Subsequent experiments used root growth rates to determine when seminal root tips first came into contact with drying soil, with the intentions of determining how the observed root growth rates were maintained as an explanation for the observed changes in root allocation. Measurements of seminal root ABA and ethylene from roots within the drying soil are interpreted with respect to what is known about the physiological control of root growth in drying soil. Copyright © 2018 Elsevier GmbH. All rights reserved.

Intensive field phenotyping of maize (Zea mays L.) root crowns identifies phenes and phene integration associated with plant growth and nitrogen acquisition.

PubMed

York, Larry M; Lynch, Jonathan P

2015-09-01

Root architecture is an important regulator of nitrogen (N) acquisition. Existing methods to phenotype the root architecture of cereal crops are generally limited to seedlings or to the outer roots of mature root crowns. The functional integration of root phenes is poorly understood. In this study, intensive phenotyping of mature root crowns of maize was conducted to discover phenes and phene modules related to N acquisition. Twelve maize genotypes were grown under replete and deficient N regimes in the field in South Africa and eight in the USA. An image was captured for every whorl of nodal roots in each crown. Custom software was used to measure root phenes including nodal occupancy, angle, diameter, distance to branching, lateral branching, and lateral length. Variation existed for all root phenes within maize root crowns. Size-related phenes such as diameter and number were substantially influenced by nodal position, while angle, lateral density, and distance to branching were not. Greater distance to branching, the length from the shoot to the emergence of laterals, is proposed to be a novel phene state that minimizes placing roots in already explored soil. Root phenes from both older and younger whorls of nodal roots contributed to variation in shoot mass and N uptake. The additive integration of root phenes accounted for 70% of the variation observed in shoot mass in low N soil. These results demonstrate the utility of intensive phenotyping of mature root systems, as well as the importance of phene integration in soil resource acquisition. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Profiling of differentially expressed genes critical to storage root development in hydroponically and in-vitro grown sweetpotato for space farming

NASA Astrophysics Data System (ADS)

Egnin, M.; Gao, H.; He, G.; Woullard, F.; Mortley, D.; Scoffield, J.; Bey, B.; Quain, M.; Prakash, C. S.; Bonsi, C.

Environment is known to have significant effects on the nutrient content and quality of crop plants especially through its impact on the temporal and spatial expression of genes Little is known about the molecular changes and harvest index in plants in response to microgravity Sweetpotato underline Ipomoea underline batatas L Lam is one of the most important root crops and an excellent NASA crop for space farming to provide essential nutrients to sustain human life on long-term space missions The initiation and development of storage root formation is one of the most critical processes determining yield of sweetpotato The molecular mechanism of storage root initiation and development in sweetpotato is poorly understood To this end knowledge of gravity perception the genetic and molecular nature of the induction process of storage root will tremendously help improve on sweetpotato harvest index for space farming cDNA-AFLP techniques were employed to investigate temporal and spatial expressions to gain molecular insights and identify transcripts differentially expressed during early stages of sweetpotato storage root development Two hydroponically grown cultivars using Nutrient Film Technology NFT and microstorage roots were evaluated TU-82-155 an early maturing 90 DAP with orange flesh and tinge red skin and PI318846-3 a late maturing 135 DAP with white flesh and off-yellow skin were compared for differential genes expression during storage root development at 14 21 28 35 and 45 DAP Total RNA was isolated from

Role of Root Hairs and Lateral Roots in Silicon Uptake by Rice

PubMed Central

Ma, Jian Feng; Goto, Shoko; Tamai, Kazunori; Ichii, Masahiko

2001-01-01

The rice plant (Oryza sativa L. cv Oochikara) is known to be a Si accumulator, but the mechanism responsible for the high uptake of Si by the roots is not well understood. We investigated the role of root hairs and lateral roots in the Si uptake using two mutants of rice, one defective in the formation of root hairs (RH2) and another in that of lateral roots (RM109). Uptake experiments with nutrient solution during both a short term (up to 12 h) and relatively long term (26 d) showed that there was no significant difference in Si uptake between RH2 and the wild type (WT), whereas the Si uptake of RM109 was much less than that of WT. The number of silica bodies formed on the third leaf in RH2 was similar to that in WT, but the number of silica bodies in RM109 was only 40% of that in WT, when grown in soil amended with Si under flooded conditions. There was also no difference in the shoot Si concentration between WT and RH2 when grown in soil under upland conditions. Using a multi-compartment transport box, the Si uptake at the root tip (0–1 cm, without lateral roots and root hairs) was found to be similar in WT, RH2, and RM109. However, the Si uptake in the mature zone (1–4 cm from root tip) was significantly lower in RM109 than in WT, whereas no difference was found in Si uptake between WT and RH2. All these results clearly indicate that lateral roots contribute to the Si uptake in rice plant, whereas root hairs do not. Analysis of F2 populations between RM109 and WT showed that Si uptake was correlated with the presence of lateral roots and that the gene controlling formation of lateral roots and Si uptake is a dominant gene. PMID:11743120

Experimentally reduced root–microbe interactions reveal limited plasticity in functional root traits in Acer and Quercus

PubMed Central

Lee, Mei-Ho; Comas, Louise H.; Callahan, Hilary S.

2014-01-01

Background and Aims Interactions between roots and soil microbes are critical components of below-ground ecology. It is essential to quantify the magnitude of root trait variation both among and within species, including variation due to plasticity. In addition to contextualizing the magnitude of plasticity relative to differences between species, studies of plasticity can ascertain if plasticity is predictable and whether an environmental factor elicits changes in traits that are functionally advantageous. Methods To compare functional traits and trait plasticities in fine root tissues with natural and reduced levels of colonization by microbial symbionts, trimmed and surface-sterilized root segments of 2-year-old Acer rubrum and Quercus rubra seedlings were manipulated. Segments were then replanted into satellite pots filled with control or heat-treated soil, both originally derived from a natural forest. Mycorrhizal colonization was near zero in roots grown in heat-treated soil; roots grown in control soil matched the higher colonization levels observed in unmanipulated root samples collected from field locations. Key Results Between-treatment comparisons revealed negligible plasticity for root diameter, branching intensity and nitrogen concentration across both species. Roots from treated soils had decreased tissue density (approx. 10–20 %) and increased specific root length (approx. 10–30 %). In contrast, species differences were significant and greater than treatment effects in traits other than tissue density. Interspecific trait differences were also significant in field samples, which generally resembled greenhouse samples. Conclusions The combination of experimental and field approaches was useful for contextualizing trait plasticity in comparison with inter- and intra-specific trait variation. Findings that root traits are largely species dependent, with the exception of root tissue density, are discussed in the context of current literature on root trait variation, interactions with symbionts and recent progress in standardization of methods for quantifying root traits. PMID:24363335

Establishment of Hairy Root Cultures by Agrobacterium Rhizogenes Mediated Transformation of Isatis Tinctoria L. for the Efficient Production of Flavonoids and Evaluation of Antioxidant Activities

PubMed Central

Luo, Meng; Wei, Zuo-Fu; Zu, Yuan-Gang; Ma, Wei; Fu, Yu-Jie

2015-01-01

In this work, Isatis tinctoria hairy root cultures (ITHRCs) were established as an alternative source for flavonoids (FL) production. I. tinctoria hairy root line V was found to be the most efficient line and was further confirmed by the PCR amplification of rolB, rolC and aux1 genes. Culture parameters of ITHRCs were optimized by Box-Behnken design (BBD), and eight bioactive FL constituents (rutin, neohesperidin, buddleoside, liquiritigenin, quercetin, isorhamnetin, kaempferol and isoliquiritigenin) were quali-quantitatively determined by LC-MS/MS. Under optimal conditions, the total FL accumulation of ITHRCs (24 day-old) achieved was 438.10 μg/g dry weight (DW), which exhibited significant superiority as against that of 2 year-old field grown roots (341.73 μg/g DW). Additionally, in vitro antioxidant assays demonstrated that ITHRCs extracts exhibited better antioxidant activities with lower IC50 values (0.41 and 0.39, mg/mL) as compared to those of field grown roots (0.56 and 0.48, mg/mL). To the best of our knowledge, this is the first report describing FL production and antioxidant activities from ITHRCs. PMID:25785699

Establishment of hairy root cultures by Agrobacterium rhizogenes mediated transformation of Isatis tinctoria L. For the efficient production of flavonoids and evaluation of antioxidant activities.

PubMed

Gai, Qing-Yan; Jiao, Jiao; Luo, Meng; Wei, Zuo-Fu; Zu, Yuan-Gang; Ma, Wei; Fu, Yu-Jie

2015-01-01

In this work, Isatis tinctoria hairy root cultures (ITHRCs) were established as an alternative source for flavonoids (FL) production. I. tinctoria hairy root line V was found to be the most efficient line and was further confirmed by the PCR amplification of rolB, rolC and aux1 genes. Culture parameters of ITHRCs were optimized by Box-Behnken design (BBD), and eight bioactive FL constituents (rutin, neohesperidin, buddleoside, liquiritigenin, quercetin, isorhamnetin, kaempferol and isoliquiritigenin) were quali-quantitatively determined by LC-MS/MS. Under optimal conditions, the total FL accumulation of ITHRCs (24 day-old) achieved was 438.10 μg/g dry weight (DW), which exhibited significant superiority as against that of 2 year-old field grown roots (341.73 μg/g DW). Additionally, in vitro antioxidant assays demonstrated that ITHRCs extracts exhibited better antioxidant activities with lower IC₅₀ values (0.41 and 0.39, mg/mL) as compared to those of field grown roots (0.56 and 0.48, mg/mL). To the best of our knowledge, this is the first report describing FL production and antioxidant activities from ITHRCs.

Severely Reduced Gravitropism in Dark-Grown Hypocotyls of a Starch-Deficient Mutant of Nicotiana sylvestris1

PubMed Central

Kiss, John Z.; Sack, Fred D.

1990-01-01

Gravitropism in dark-grown hypocotyls of the wild type was compared with a starch-deficient Nicotiana sylvestris mutant (NS 458) to test the effects of starch deficiency on gravity sensing. In a time course of curvature measured using infrared video, the response of the mutant was greatly reduced compared to the wild type; 72 hours after reorientation, curvature was about 10° for NS 458 and about 70° for wild type. In dishes maintained in a vertical orientation, wild-type hypocotyls were predominantly vertical, whereas NS 458 hypocotyls were severely disoriented with about 5 times more orientational variability than wild type. Since the growth rates were equal for both genotypes and phototropic curvature was only slightly inhibited in NS 458, the mutation probably affects gravity perception rather than differential growth. Our data suggest that starch deficiency reduces gravitropic sensitivity more in dark-grown hypocotyls than in dark- or light-grown roots in this mutant and support the hypothesis that amyloplasts function as statoliths in shoots as well as roots. Images Figure 2 Figure 3 Figure 4 PMID:11537476

Severely reduced gravitropism in dark-grown hypocotyls of a starch-deficient mutant of Nicotiana sylvestris

NASA Technical Reports Server (NTRS)

Kiss, J. Z.; Sack, F. D.

1990-01-01

Gravitropism in dark-grown hypocotyls of the wild type was compared with a starch-deficient Nicotiana sylvestris mutant (NS 458) to test the effects of starch deficiency on gravity sensing. In a time course of curvature measured using infrared video, the response of the mutant was greatly reduced compared to the wild type; 72 hours after reorientation, curvature was about 10 degrees for NS 458 and about 70 degrees for wild type. In dishes maintained in a vertical orientation, wild-type hypocotyls were predominantly vertical, whereas NS 458 hypocotyls were severely disoriented with about 5 times more orientational variability than wild type. Since the growth rates were equal for both genotypes and phototropic curvature was only slightly inhibited in NS 458, the mutation probably affects gravity perception rather than differential growth. Our data suggest that starch deficiency reduces gravitropic sensitivity more in dark-grown hypocotyls than in dark- or light-grown roots in this mutant and support the hypothesis that amyloplasts function as statoliths in shoots as well as roots.

Growth and Flowering Responses of Cut Chrysanthemum Grown under Restricted Root Volume to Irrigation Frequency

PubMed Central

Taweesak, Viyachai; Lee Abdullah, Thohirah; Hassan, Siti Aishah; Kamarulzaman, Nitty Hirawaty; Wan Yusoff, Wan Abdullah

2014-01-01

Influences of irrigation frequency on the growth and flowering of chrysanthemum grown under restricted root volume were tested. Chrysanthemum cuttings (Chrysanthemum morifolium “Reagan White”) were grown in seedling tray which contained coconut peat in volumes of 73 and 140 cm3. Plants were irrigated with drip irrigation at irrigation frequencies of 4 (266 mL), 6 (400 mL), and 8 (533 mL) times/day to observe their growth and flowering performances. There was interaction between irrigation frequency and substrate volume on plant height of chrysanthemum. Plants grown in 140 cm3 substrates and irrigated 6 times/day produced the tallest plant of 109.25 cm. Plants irrigated 6 and 8 times/day had significantly higher level of phosphorus content in their leaves than those plants irrigated 4 times/day. The total leaf area, number of internodes, leaf length, and leaf width of chrysanthemums grown in 140 cm3 substrate were significantly higher than those grown in 73 cm3 substrate. The numbers of flowers were affected by both irrigation frequencies and substrate volumes. Chrysanthemums irrigated 8 times/day had an average of 19.56 flowers while those irrigated 4 times/day had an average of 16.63 flowers. Increasing irrigation frequency can improve the growth and flowering of chrysanthemums in small substrate volumes. PMID:25478586

Arabidopsis thaliana root elongation growth is sensitive to lunisolar tidal acceleration and may also be weakly correlated with geomagnetic variations.

PubMed

Barlow, Peter W; Fisahn, Joachim; Yazdanbakhsh, Nima; Moraes, Thiago A; Khabarova, Olga V; Gallep, Cristiano M

2013-05-01

Correlative evidence suggests a relationship between the lunisolar tidal acceleration and the elongation rate of arabidopsis roots grown under free-running conditions of constant low light. Seedlings of Arabidopsis thaliana were grown in a controlled-climate chamber maintained at a constant temperature and subjected to continuous low-level illumination from fluorescent tubes, conditions that approximate to a 'free-running' state in which most of the abiotic factors that entrain root growth rates are excluded. Elongation of evenly spaced, vertical primary roots was recorded continuously over periods of up to 14 d using high temporal- and spatial-resolution video imaging and were analysed in conjunction with geophysical variables. The results confirm the lunisolar tidal/root elongation relationship. Also presented are relationships between the hourly elongation rates and the contemporaneous variations in geomagnetic activity, as evaluated from the disturbance storm time and ap indices. On the basis of time series of root elongation rates that extend over ≥4 d and recorded at different seasons of the year, a provisional conclusion is that root elongation responds to variation in the lunisolar force and also appears to adjust in accordance with variations in the geomagnetic field. Thus, both lunisolar tidal acceleration and the geomagnetic field should be considered as modulators of root growth rate, alongside other, stronger and more well-known abiotic environmental regulators, and perhaps unexplored factors such as air ions. Major changes in atmospheric pressure are not considered to be a factor contributing to oscillations of root elongation rate.

Arabidopsis thaliana root elongation growth is sensitive to lunisolar tidal acceleration and may also be weakly correlated with geomagnetic variations

PubMed Central

Barlow, Peter W.; Fisahn, Joachim; Yazdanbakhsh, Nima; Moraes, Thiago A.; Khabarova, Olga V.; Gallep, Cristiano M.

2013-01-01

Background Correlative evidence suggests a relationship between the lunisolar tidal acceleration and the elongation rate of arabidopsis roots grown under free-running conditions of constant low light. Methods Seedlings of Arabidopsis thaliana were grown in a controlled-climate chamber maintained at a constant temperature and subjected to continuous low-level illumination from fluorescent tubes, conditions that approximate to a ‘free-running’ state in which most of the abiotic factors that entrain root growth rates are excluded. Elongation of evenly spaced, vertical primary roots was recorded continuously over periods of up to 14 d using high temporal- and spatial-resolution video imaging and were analysed in conjunction with geophysical variables. Key Results and Conclusions The results confirm the lunisolar tidal/root elongation relationship. Also presented are relationships between the hourly elongation rates and the contemporaneous variations in geomagnetic activity, as evaluated from the disturbance storm time and ap indices. On the basis of time series of root elongation rates that extend over ≥4 d and recorded at different seasons of the year, a provisional conclusion is that root elongation responds to variation in the lunisolar force and also appears to adjust in accordance with variations in the geomagnetic field. Thus, both lunisolar tidal acceleration and the geomagnetic field should be considered as modulators of root growth rate, alongside other, stronger and more well-known abiotic environmental regulators, and perhaps unexplored factors such as air ions. Major changes in atmospheric pressure are not considered to be a factor contributing to oscillations of root elongation rate. PMID:23532042

Characterization of a novel, ubiquitous fungal endophyte from the rhizosphere and root endosphere of Populus trees

DOE PAGES

Vélez, Jessica M.; Tschaplinski, Timothy J.; Vilgalys, Rytas; ...

2017-04-07

Here, we examined variation in growth rate, patterns of nitrogen utilization, and competitive interactions of Atractiellarhizophila isolates from the roots of Populus hosts. Atractiella grew significantly faster on media substituted with inorganic nitrogen sources and slower in the presence of another fungal genus. In order to determine plausible causal mechanisms we used metabolomics to explore competitive interactions between Atractiella strains and Fusarium oxysporum or Leptosphaerulina chartarum. Metabolomic screening of potential microbial inhibitors showed increased levels of glycosides produced in vitro by Atractiella when grown with a different fungal genus, relative to when grown alone. Overall, our results suggest Atractiella ismore » a poor competitor with other fungi via direct routes e.g. faster growth rates, but may utilize chemical interactions and possibly nitrogen sources to defend itself, and niche partition its way to abundance in the plant host root and rhizosphere.« less

Host Status of Seven Weed Species and Their Effects on Ditylenchus destructor Infestation of Peanut.

PubMed

De Waele, D; Jordaan, E M; Basson, S

1990-07-01

The host suitability to Ditylenchus destructor of seven common weed species in peanut (Arachis hypogaea) fields in South Africa was determined. Based on the number of nematodes per root unit, white goosefoot (Chenopodium album), feathertop chloris (Chloris virgata), purple nutsedge (Cyperus rotundus), jimson weed (Datura stramonium), goose grass (Eleusine indica), khaki weed (Tagetes minuta), and cocklebur (Xanthium strumarium) were poor hosts. Ditylenchus destructor survived on all weed species; population densities increased in peanut hulls and caused severe damage to seeds of peanut grown after weeds. Roots of purple nutsedge left in the soil suppressed populations of D. destructor and root and pod development in peanut grown after the weed. However, nematode populations in peanut hulls and seeds were not suppressed. Some weed species, especially purple nutsedge which is common in peanut fields, can be used to indicate the presence of D. destructor in the absence of peanut.

Host Status of Seven Weed Species and Their Effects on Ditylenchus destructor Infestation of Peanut

PubMed Central

De Waele, D.; Jordaan, Elizabeth M.; Basson, Selmaré

1990-01-01

The host suitability to Ditylenchus destructor of seven common weed species in peanut (Arachis hypogaea) fields in South Africa was determined. Based on the number of nematodes per root unit, white goosefoot (Chenopodium album), feathertop chloris (Chloris virgata), purple nutsedge (Cyperus rotundus), jimson weed (Datura stramonium), goose grass (Eleusine indica), khaki weed (Tagetes minuta), and cocklebur (Xanthium strumarium) were poor hosts. Ditylenchus destructor survived on all weed species; population densities increased in peanut hulls and caused severe damage to seeds of peanut grown after weeds. Roots of purple nutsedge left in the soil suppressed populations of D. destructor and root and pod development in peanut grown after the weed. However, nematode populations in peanut hulls and seeds were not suppressed. Some weed species, especially purple nutsedge which is common in peanut fields, can be used to indicate the presence of D. destructor in the absence of peanut. PMID:19287723

Characterization of a novel, ubiquitous fungal endophyte from the rhizosphere and root endosphere of Populus trees

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vélez, Jessica M.; Tschaplinski, Timothy J.; Vilgalys, Rytas

Here, we examined variation in growth rate, patterns of nitrogen utilization, and competitive interactions of Atractiellarhizophila isolates from the roots of Populus hosts. Atractiella grew significantly faster on media substituted with inorganic nitrogen sources and slower in the presence of another fungal genus. In order to determine plausible causal mechanisms we used metabolomics to explore competitive interactions between Atractiella strains and Fusarium oxysporum or Leptosphaerulina chartarum. Metabolomic screening of potential microbial inhibitors showed increased levels of glycosides produced in vitro by Atractiella when grown with a different fungal genus, relative to when grown alone. Overall, our results suggest Atractiella ismore » a poor competitor with other fungi via direct routes e.g. faster growth rates, but may utilize chemical interactions and possibly nitrogen sources to defend itself, and niche partition its way to abundance in the plant host root and rhizosphere.« less

Comparative studies on cellular behaviour of carnation (Dianthus caryophyllus Linn. cv. Grenadin) grown in vivo and in vitro for early detection of somaclonal variation.

PubMed

Yaacob, Jamilah Syafawati; Taha, Rosna Mat; Khorasani Esmaeili, Arash

2013-01-01

The present study deals with the cytological investigations on the meristematic root cells of carnation (Dianthus caryophyllus Linn.) grown in vivo and in vitro. Cellular parameters including the mitotic index (MI), chromosome count, ploidy level (nuclear DNA content), mean cell and nuclear areas, and cell doubling time (Cdt) were determined from the 2 mm root tip segments of this species. The MI value decreased when cells were transferred from in vivo to in vitro conditions, perhaps due to early adaptations of the cells to the in vitro environment. The mean chromosome number was generally stable (2n = 2x = 30) throughout the 6-month culture period, indicating no occurrence of early somaclonal variation. Following the transfer to the in vitro environment, a significant increase was recorded for mean cell and nuclear areas, from 26.59 ± 0.09  μm² to 35.66 ± 0.10  μm² and 142.90 ± 0.59  μm² to 165.05 ± 0.58  μm², respectively. However, the mean cell and nuclear areas of in vitro grown D. caryophyllus were unstable and fluctuated throughout the tissue culture period, possibly due to organogenesis or rhizogenesis. Ploidy level analysis revealed that D. caryophyllus root cells contained high percentage of polyploid cells when grown in vivo and maintained high throughout the 6-month culture period.

Comparative Studies on Cellular Behaviour of Carnation (Dianthus caryophyllus Linn. cv. Grenadin) Grown In Vivo and In Vitro for Early Detection of Somaclonal Variation

PubMed Central

Yaacob, Jamilah Syafawati; Taha, Rosna Mat; Khorasani Esmaeili, Arash

2013-01-01

The present study deals with the cytological investigations on the meristematic root cells of carnation (Dianthus caryophyllus Linn.) grown in vivo and in vitro. Cellular parameters including the mitotic index (MI), chromosome count, ploidy level (nuclear DNA content), mean cell and nuclear areas, and cell doubling time (Cdt) were determined from the 2 mm root tip segments of this species. The MI value decreased when cells were transferred from in vivo to in vitro conditions, perhaps due to early adaptations of the cells to the in vitro environment. The mean chromosome number was generally stable (2n = 2x = 30) throughout the 6-month culture period, indicating no occurrence of early somaclonal variation. Following the transfer to the in vitro environment, a significant increase was recorded for mean cell and nuclear areas, from 26.59 ± 0.09 μm2 to 35.66 ± 0.10 μm2 and 142.90 ± 0.59 μm2 to 165.05 ± 0.58 μm2, respectively. However, the mean cell and nuclear areas of in vitro grown D. caryophyllus were unstable and fluctuated throughout the tissue culture period, possibly due to organogenesis or rhizogenesis. Ploidy level analysis revealed that D. caryophyllus root cells contained high percentage of polyploid cells when grown in vivo and maintained high throughout the 6-month culture period. PMID:23766703

Trait-based characterisation of soil exploitation strategies of banana, weeds and cover plant species

PubMed Central

Tardy, Florence; Damour, Gaëlle; Dorel, Marc; Moreau, Delphine

2017-01-01

Cover plants can be introduced in cropping systems to provide agroecosystem services, including weed control via competition for resources. There is currently no consensus on how to identify the best cover plant species, while trait-based approaches are promising for screening plant species due to their agroecosystem service provision potential. This study was carried out to characterize soil exploitation strategies of cover plant species in banana agroecosystems using a trait-based approach, and in turn identify cover plant species with a high weed control potential via competition for soil resources in banana cropping systems. A field experiment was conducted on 17 cover plant species, two weed species and two banana cultivars grown individually. Four functional traits were measured. Two of them (i.e., the size of the zone explored by roots and the root impact density) were used to characterize root system soil exploration patterns. Two other traits (i.e., specific root length and root diameter) were used to characterize resource acquisition within the soil zone explored by the roots. All studied traits exhibited marked variations among species. The findings suggested a trade-off between the abilities of species to develop a limited number of large diameter roots exploring a large soil zone versus many thin roots exploring a smaller soil zone. Three soil-resource exploitation strategies were identified among species: (i) with large diameter roots that explore a large soil zone; (ii) with small diameter roots and a high specific length that explore a smaller soil zone; and (iii) with a high total root-impact density and an intermediate specific root length that explore the uppermost soil layers. Interestingly, in our panel of species, no correlations with regard to belowground and aboveground strategies were noted: species with an acquisitive belowground strategy could display an acquisitive or a conservative aboveground strategy. The findings of this study illustrated that a trait-based approach could be used to identify plant species with potential for competing with weeds, while minimising competition with banana. Six of the 17 studied cover crop species were identified as having this potential. The next step will be to assess them for their weed control performances in banana cropping systems with low reliance on herbicides. PMID:28257454

Trait-based characterisation of soil exploitation strategies of banana, weeds and cover plant species.

PubMed

Tardy, Florence; Damour, Gaëlle; Dorel, Marc; Moreau, Delphine

2017-01-01

Cover plants can be introduced in cropping systems to provide agroecosystem services, including weed control via competition for resources. There is currently no consensus on how to identify the best cover plant species, while trait-based approaches are promising for screening plant species due to their agroecosystem service provision potential. This study was carried out to characterize soil exploitation strategies of cover plant species in banana agroecosystems using a trait-based approach, and in turn identify cover plant species with a high weed control potential via competition for soil resources in banana cropping systems. A field experiment was conducted on 17 cover plant species, two weed species and two banana cultivars grown individually. Four functional traits were measured. Two of them (i.e., the size of the zone explored by roots and the root impact density) were used to characterize root system soil exploration patterns. Two other traits (i.e., specific root length and root diameter) were used to characterize resource acquisition within the soil zone explored by the roots. All studied traits exhibited marked variations among species. The findings suggested a trade-off between the abilities of species to develop a limited number of large diameter roots exploring a large soil zone versus many thin roots exploring a smaller soil zone. Three soil-resource exploitation strategies were identified among species: (i) with large diameter roots that explore a large soil zone; (ii) with small diameter roots and a high specific length that explore a smaller soil zone; and (iii) with a high total root-impact density and an intermediate specific root length that explore the uppermost soil layers. Interestingly, in our panel of species, no correlations with regard to belowground and aboveground strategies were noted: species with an acquisitive belowground strategy could display an acquisitive or a conservative aboveground strategy. The findings of this study illustrated that a trait-based approach could be used to identify plant species with potential for competing with weeds, while minimising competition with banana. Six of the 17 studied cover crop species were identified as having this potential. The next step will be to assess them for their weed control performances in banana cropping systems with low reliance on herbicides.

Sennosides A and B production by hairy roots of Senna alata (L.) Roxb.

PubMed

Putalun, Waraporn; Pimmeuangkao, Suwat; De-Eknamkul, Wanchai; Tanaka, Hiroyuki; Shoyama, Yukihiro

2006-01-01

Hairy roots of Senna alata transformed with Agrobacterium rhizogenes, strain ATCC 15834 were induced and grown in half-strength Murashige and Skoog (MS) medium. Effects of sucrose contents and hormones on the growth and sennosides A, B production were investigated. Hairy roots cultured on hormone-free half-strength MS medium containing 5% sucrose under dark condition mostly stimulated the growth of hairy roots and increased the content of sennosides A and B yielding (169 +/- 4) and (34 +/- 3) microg g(-1) dry wt, respectively.

Light as stress factor to plant roots – case of root halotropism

PubMed Central

Yokawa, Ken; Fasano, Rossella; Kagenishi, Tomoko; Baluška, František

2014-01-01

Despite growing underground, largely in darkness, roots emerge to be very sensitive to light. Recently, several important papers have been published which reveal that plant roots not only express all known light receptors but also that their growth, physiology and adaptive stress responses are light-sensitive. In Arabidopsis, illumination of roots speeds-up root growth via reactive oxygen species-mediated and F-actin dependent process. On the other hand, keeping Arabidopsis roots in darkness alters F-actin distribution, polar localization of PIN proteins as well as polar transport of auxin. Several signaling components activated by phytohormones are overlapping with light-related signaling cascade. We demonstrated that the sensitivity of roots to salinity is altered in the light-grown Arabidopsis roots. Particularly, light-exposed roots are less effective in their salt-avoidance behavior known as root halotropism. Here we discuss these new aspects of light-mediated root behavior from cellular, physiological and evolutionary perspectives. PMID:25566292

Effects of co-inoculation with arbuscular mycorrhizal fungi and rhizobia on soybean growth as related to root architecture and availability of N and P.

PubMed

Wang, Xiurong; Pan, Qiang; Chen, Fengxian; Yan, Xiaolong; Liao, Hong

2011-04-01

Soybean plants can form tripartite symbiotic associations with rhizobia and arbuscular mycorrhizal (AM) fungi, but little is known about effects of co-inoculation with rhizobia and AM fungi on plant growth, or their relationships to root architecture as well as nitrogen (N) and phosphorus (P) availability. In the present study, two soybean genotypes contrasting in root architecture were grown in a field experiment to evaluate relationships among soybean root architecture, AMF colonization, and nodulation under natural conditions. Additionally, a soil pot experiment in greenhouse was conducted to investigate the effects of co-inoculation with rhizobia and AM fungi on soybean growth, and uptake of N and P. Our results indicated that there was a complementary relationship between root architecture and AMF colonization in the field. The deep root soybean genotype had greater AMF colonization at low P, but better nodulation with high P supply than the shallow root genotype. A synergistic relationship dependent on N and P status exists between rhizobia and AM fungi on soybean growth. Co-inoculation with rhizobia and AM fungi significantly increased soybean growth under low P and/or low N conditions as indicated by increased shoot dry weight, along with plant N and P content. There were no significant effects of inoculation under adequate N and P conditions. Furthermore, the effects of co-inoculation were related to root architecture. The deep root genotype, HN112, benefited more from co-inoculation than the shallow root genotype, HN89. Our results elucidate new insights into the relationship between rhizobia, AM fungi, and plant growth under limitation of multiple nutrients, and thereby provides a theoretical basis for application of co-inoculation in field-grown soybean.

Gravity-dependent differentiation and root coils in Arabidopsis thaliana wild type and phospholipase-A-I knockdown mutant grown on the International Space Station.

PubMed

Scherer, G F E; Pietrzyk, P

2014-01-01

Arabidopsis roots on 45° tilted agar in 1-g grow in wave-like figures. In addition to waves, formation of root coils is observed in several mutants compromised in gravitropism and/or auxin transport. The knockdown mutant ppla-I-1 of patatin-related phospholipase-A-I is delayed in root gravitropism and forms increased numbers of root coils. Three known factors contribute to waving: circumnutation, gravisensing and negative thigmotropism. In microgravity, deprivation of wild type (WT) and mutant roots of gravisensing and thigmotropism and circumnutation (known to slow down in microgravity, and could potentially lead to fewer waves or increased coiling in both WT and mutant). To resolve this, mutant ppla-I-1 and WT were grown in the BIOLAB facility in the International Space Station. In 1-g, roots of both types only showed waving. In the first experiment in microgravity, the mutant after 9 days formed far more coils than in 1-g but the WT also formed several coils. After 24 days in microgravity, in both types the coils were numerous with slightly more in the mutant. In the second experiment, after 9 days in microgravity only the mutant formed coils and the WT grew arcuated roots. Cell file rotation (CFR) on the mutant root surface in microgravity decreased in comparison to WT, and thus was not important for coiling. Several additional developmental responses (hypocotyl elongation, lateral root formation, cotyledon expansion) were found to be gravity-influenced. We tentatively discuss these in the context of disturbances in auxin transport, which are known to decrease through lack of gravity. © 2013 German Botanical Society and The Royal Botanical Society of the Netherlands.

Chemistry and long-term decomposition of roots of Douglas-fir grown under elevated atmospheric carbon dioxide and warming conditions.

PubMed

Chen, H; Rygiewicz, P T; Johnson, M G; Harmon, M E; Tian, H; Tang, J W

2008-01-01

Elevated atmospheric CO(2) concentrations and warming may affect the quality of litters of forest plants and their subsequent decomposition in ecosystems, thereby potentially affecting the global carbon cycle. However, few data on root tissues are available to test this feedback to the atmosphere. In this study, we used fine (diameter < or = 2 mm) and small (2-10 mm) roots of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) seedlings that were grown for 4 yr in a 2 x 2 factorial experiment: ambient or elevated (+ 180 ppm) atmospheric CO(2) concentrations, and ambient or elevated (+3.8 degrees C) atmospheric temperature. Exposure to elevated CO(2) significantly increased water-soluble extractives concentration (%WSE), but had little effect on the concentration of N, cellulose, and lignin of roots. Elevated temperature had no effect on substrate quality except for increasing %WSE and decreasing the %lignin content of fine roots. No significant interaction was found between CO(2) and temperature treatments on substrate quality, except for %WSE of the fine roots. Short-term (< or = 9 mo) root decomposition in the field indicated that the roots from the ambient CO(2) and ambient temperature treatment had the slowest rate. However, over a longer period of incubation (9-36 mo) the influence of initial substrate quality on root decomposition diminished. Instead, the location of the field incubation sites exhibited significant control on decomposition. Roots at the warmer, low elevation site decomposed significantly faster than the ones at the cooler, high elevation site. This study indicates that short-term decomposition and long-term responses are not similar. It also suggests that increasing atmospheric CO(2) had little effect on the carbon storage of Douglas-fir old-growth forests of the Pacific Northwest.

Localization and Speciation of Arsenic in Soil and Desert Plant Parkinsonia florida using μXRF and μXANES

PubMed Central

Castillo-Michel, Hiram; Hernandez-Viezcas, Jose; Dokken, Kenneth M.; Marcus, Matthew A.; Peralta-Videa, Jose R.; Gardea-Torresdey, Jorge L.

2011-01-01

Parkinsonia florida is a plant species native to the semi-desert regions of North America. The cultivation characteristics of this shrub/tree suggest that it could be used for phytoremediation purposes in semiarid regions. This work describes, through the use of synchrotron μXRF and μXANES techniques and ICP-OES, the arsenic (As) accumulation and distribution in P. florida plants grown in two soils spiked with As at 20 mg kg-1. Plants grown in a sandy soil accumulated at least twice more As in the roots compared to plants grown in a loamy soil. The lower As accumulation in plants grown in the loamy soil corresponded to a lower concentration of As in the water soluble fraction (WSF) of this soil. LC-ICP-MS speciation analysis showed only As(V) in the WSF from all treatments. In contrast, linear combination XANES speciation analysis from the root tissues showed As mainly present in the reduced As(III) form. Moreover, a fraction of the reduced As was found coordinating to S in a form consistent with As-Cys3. The percentage of As coordinated to sulfur was smaller for plants grown in the loamy soil when compared to the sandy soil. PMID:21842861

Localization and speciation of arsenic in soil and desert plant Parkinsonia florida using μXRF and μXANES.

PubMed

Castillo-Michel, Hiram; Hernandez-Viezcas, Jose; Dokken, Kenneth M; Marcus, Matthew A; Peralta-Videa, Jose R; Gardea-Torresdey, Jorge L

2011-09-15

Parkinsonia florida is a plant species native to the semidesert regions of North America. The cultivation characteristics of this shrub/tree suggest that it could be used for phytoremediation purposes in semiarid regions. This work describes, through the use of synchrotron μXRF and μXANES techniques and ICP-OES, the arsenic (As) accumulation and distribution in P. florida plants grown in two soils spiked with As at 20 mg kg(-1). Plants grown in a sandy soil accumulated at least twice more As in the roots compared to plants grown in a loamy soil. The lower As accumulation in plants grown in the loamy soil corresponded to a lower concentration of As in the water-soluble fraction (WSF) of this soil. LC-ICP-MS speciation analysis showed only As(V) in the WSF from all treatments. In contrast, linear combination XANES speciation analysis from the root tissues showed As mainly present in the reduced As(III) form. Moreover, a fraction of the reduced As was found coordinating to S in a form consistent with As-Cys(3). The percentage of As coordinated to sulfur was smaller for plants grown in the loamy soil when compared to the sandy soil.

Integrating biological treatment of crop residue into a hydroponic sweetpotato culture

NASA Astrophysics Data System (ADS)

Trotman, A. A.; David, P. P.; Bonsi, C. K.; Hill, W. A.; Mortley, D. G.; Loretan, P. A.

1997-01-01

Residual biomass from hydroponic culture of sweetpotato [Ipomoea batatas (L.) Lam.] was degraded using natural bacterial soil isolates. Sweetpotato was grown for 120 days in hydroponic culture with a nutrient solution comprised of a ratio of 80% modified half Hoagland solution to 20% filtered effluent from an aerobic starch hydrolysis bioreactor. The phytotoxicity of the effluent was assayed with `Waldmann's Green' lettuce (Lactuca sativa L.) and the ratio selected after a 60-day bioassay using sweetpotato plants propagated vegetatively from cuttings. Controlled environment chamber experiments were conducted to investigate the impact of filtrate from biological treatment of crop residue on growth and storage root production with plants grown in a modified half Hoagland solution. Incorporation of bioreactor effluent, reduced storage root yield of `Georgia Jet' sweetpotato but the decrease was not statistically significant when compared with yield for plants cultured in a modified half Hoagland solution without filtrate. However, yield of `TU-82-155' sweetpotato was significantly reduced when grown in a modified half Hoagland solution into which filtered effluent had been incorporated. Total biomass was significantly reduced for both sweetpotato cultivars when grown in bioreactor effluent. The leaf area and dry matter accumulation were significantly (P < 0.05) reduced for both cultivars when grown in solution culture containing 20% filtered effluent.

Developmental morphology of cover crop species exhibit contrasting behaviour to changes in soil bulk density, revealed by X-ray computed tomography

PubMed Central

Burr-Hersey, Jasmine E.; Mooney, Sacha J.; Bengough, A. Glyn; Mairhofer, Stefan

2017-01-01

Plant roots growing through soil typically encounter considerable structural heterogeneity, and local variations in soil dry bulk density. The way the in situ architecture of root systems of different species respond to such heterogeneity is poorly understood due to challenges in visualising roots growing in soil. The objective of this study was to visualise and quantify the impact of abrupt changes in soil bulk density on the roots of three cover crop species with contrasting inherent root morphologies, viz. tillage radish (Raphanus sativus), vetch (Vicia sativa) and black oat (Avena strigosa). The species were grown in soil columns containing a two-layer compaction treatment featuring a 1.2 g cm-3 (uncompacted) zone overlaying a 1.4 g cm-3 (compacted) zone. Three-dimensional visualisations of the root architecture were generated via X-ray computed tomography, and an automated root-segmentation imaging algorithm. Three classes of behaviour were manifest as a result of roots encountering the compacted interface, directly related to the species. For radish, there was switch from a single tap-root to multiple perpendicular roots which penetrated the compacted zone, whilst for vetch primary roots were diverted more horizontally with limited lateral growth at less acute angles. Black oat roots penetrated the compacted zone with no apparent deviation. Smaller root volume, surface area and lateral growth were consistently observed in the compacted zone in comparison to the uncompacted zone across all species. The rapid transition in soil bulk density had a large effect on root morphology that differed greatly between species, with major implications for how these cover crops will modify and interact with soil structure. PMID:28753645

Developmental morphology of cover crop species exhibit contrasting behaviour to changes in soil bulk density, revealed by X-ray computed tomography.

PubMed

Burr-Hersey, Jasmine E; Mooney, Sacha J; Bengough, A Glyn; Mairhofer, Stefan; Ritz, Karl

2017-01-01

Plant roots growing through soil typically encounter considerable structural heterogeneity, and local variations in soil dry bulk density. The way the in situ architecture of root systems of different species respond to such heterogeneity is poorly understood due to challenges in visualising roots growing in soil. The objective of this study was to visualise and quantify the impact of abrupt changes in soil bulk density on the roots of three cover crop species with contrasting inherent root morphologies, viz. tillage radish (Raphanus sativus), vetch (Vicia sativa) and black oat (Avena strigosa). The species were grown in soil columns containing a two-layer compaction treatment featuring a 1.2 g cm-3 (uncompacted) zone overlaying a 1.4 g cm-3 (compacted) zone. Three-dimensional visualisations of the root architecture were generated via X-ray computed tomography, and an automated root-segmentation imaging algorithm. Three classes of behaviour were manifest as a result of roots encountering the compacted interface, directly related to the species. For radish, there was switch from a single tap-root to multiple perpendicular roots which penetrated the compacted zone, whilst for vetch primary roots were diverted more horizontally with limited lateral growth at less acute angles. Black oat roots penetrated the compacted zone with no apparent deviation. Smaller root volume, surface area and lateral growth were consistently observed in the compacted zone in comparison to the uncompacted zone across all species. The rapid transition in soil bulk density had a large effect on root morphology that differed greatly between species, with major implications for how these cover crops will modify and interact with soil structure.

Change detection of cotton root rot infection over a 10-year interval using airborne multispectral imagery

USDA-ARS?s Scientific Manuscript database

Cotton root rot is a very serious and destructive disease of cotton grown in the southwestern and south central United States. Accurate information regarding the spatial and temporal infections of the disease within fields is important for effective management and control of the disease. The objecti...

Competition-Induced Reductions in Soil Water Availability Reduced Pine Root Extension Rates

Treesearch

K.H. Ludovici; L.A. Morris

1997-01-01

The relationship between soil water availability, root extension, and shoot growth of loblolly pine seedlings (Pinus taeda L.) was evaluated in a rhizotron sand mixture in the absence and presence of crabgrass (Digitaria spp.) competition. Heights and diameters of seedlings grown with crabgrass were reduced 33 and SO%, respectively, compared with...

The Development of RoBuST: An integrated genomics resource for the root and bulb crop families Apiaceae and Alliaceae

USDA-ARS?s Scientific Manuscript database

Root and bulb vegetables (RBV) include carrots, celeriac, parsnips (Apiaceae), onions, garlic, and leek (Alliaceae) – food crops that are grown globally and consumed worldwide. Few data analysis platforms are currently available where data collection, annotation and integration initiatives are focus...

First report of Phytophthora root rot, caused by Phytophthora cryptogea, on spinach in California

USDA-ARS?s Scientific Manuscript database

In 2006 and 2007, commercially grown spinach (Spinacia oleracea) in California’s coastal Salinas Valley (Monterey County) was affected by an unreported root rot disease. Disease was limited to patches along the edges of fields. Affected plants were stunted with chlorotic older leaves. As disease pro...

Chemistry and Long-Term Decomposition of Roots of Douglas-Fir Grown under Elevated Atmospheric Carbon Dioxide and Warming Conditions

EPA Science Inventory

Elevated atmospheric CO2 concentrations and warming may affect the quality of litters of forest plants and their subsequent decomposition in ecosystems, thereby potentially affecting the global carbon cycle. However, few data on root tissues are available to test this feedback to...

Responses of loblolly pine, sweetgum and crab grass roots to localized increases in nitrogen in two watering regimes

Treesearch

Kim H. Ludovici; L.A. Morris

1995-01-01

Root responses to differences in availability of nitrogen and soil water were studied in loblolly pine (Pinus taeda L.) seedlings grown in monoculture and in competition with sweetgum (Liquidambar styraciflua L.) or crab grass (Digitaria spp.). Rhizotron cells were maintained at high soil water availability (...

Development and characterization of 13 polymorphic microsatellite loci for Cryptolepsis sanguinolenta, an African antimalarial plant

USDA-ARS?s Scientific Manuscript database

Cryptolepsis sanguinolenta is an herbaceous perennial plant indigenous to West and Central Africa. The roots are harvested and widely used in the preparation of herbal decoctions to treat malaria. The process of harvesting wild grown roots is unsustainable, and the plant is becoming more difficult t...

Systemic aspergilloma post aortic root surgery following coronary artery stenting: diagnostic and management dilemma

PubMed Central

Hussein, Nabil; Qamar, Sombul; Abid, Qamar

2015-01-01

Aspergillus infections such as Aspergillus endocarditis were once relatively rare occurrences, however, due to the increased use of intracardiac devices, the incidence has grown. With mortality rates close to 100%, in medically treated cases, it is paramount that early diagnosis and treatment are performed. An immunocompetent aviculturist presented 8 months post aortic root replacement for severe aortic regurgitation with a composite graft, with central crushing chest pain. Investigations confirmed ST elevation inferior myocardial infarction due to stenosis of the origin of the right coronary artery, which was stented. Echocardiogram demonstrated a mobile mass posterior to the left ventricular outflow tract. Following referral to our cardiothoracic surgeons, a polypoidal mass covering the right ostial button was noted along with systemic complications of the disease. Emergency redo aortic valve replacement with a homograft and coronary artery bypass was performed. Histological analysis confirmed A. fumigatus and the patient was started on intravenous voriconazole. PMID:26025972

Respiration rate in maize roots is related to concentration of reduced nitrogen and proliferation of lateral roots

NASA Technical Reports Server (NTRS)

Granato, T. C.; Raper, C. D. Jr; Wilkerson, G. G.; Raper CD, J. r. (Principal Investigator)

1989-01-01

The relationship between specific rate of respiration (respiration rate per unit root dry weight) and concentration of reduced nitrogen was examined for maize (Zea mays L.) roots. Plants with 2 primary nodal root axes were grown for 8 days in a split-root hydroponic system in which NO3- was supplied to both axes at 1.0 mol m-3, to one axis at 1.0 mol m-3 and the other axis at 0.0 mol m-3, or to both axes at 0.0 mol m-3. Respiration rates and root characteristics were measured at 2-day intervals. Specific rate of respiration was positively correlated in a nonlinear relationship with concentration of reduced nitrogen. The lowest specific rates of respiration occurred when neither axis received exogenous NO3- and the concentration of reduced nitrogen in the axes was less than 9 mg g-1. The greatest rates occurred in axes that were actively absorbing NO3- and contained more than 35 mg g-1 of reduced nitrogen. At 23 mg g-1 of reduced nitrogen, below which initiation of lateral branches was decreased by 30-50%, specific rate of respiration was 17% greater for roots actively absorbing NO3- than for roots not absorbing NO3-. Increases in specific rate of respiration associated with concentrations of reduced nitrogen greater than 23 mg g-1 were concluded to be attributable primarily to proliferation of lateral branches.

Localized application of soil organic matter shifts distribution of cluster roots of white lupin in the soil profile due to localized release of phosphorus

PubMed Central

Li, Hai-Gang; Shen, Jian-Bo; Zhang, Fu-Suo; Lambers, Hans

2010-01-01

Background and Aims Phosphorus (P) is a major factor controlling cluster-root formation. Cluster-root proliferation tends to concentrate in organic matter (OM)-rich surface-soil layers, but the nature of this response of cluster-root formation to OM is not clear. Cluster-root proliferation in response to localized application of OM was characterized in Lupinus albus (white lupin) grown in stratified soil columns to test if the stimulating effect of OM on cluster-root formation was due to (a) P release from breakdown of OM; (b) a decrease in soil density; or (c) effects of micro-organisms other than releasing P from OM. Methods Lupin plants were grown in three-layer stratified soil columns where P was applied at 0 or 330 mg P kg−1 to create a P-deficient or P-sufficient background, and OM, phytate mixed with OM, or perlite was applied to the top or middle layers with or without sterilization. Key Results Non-sterile OM stimulated cluster-root proliferation and root length, and this effect became greater when phytate was supplied in the presence of OM. Both sterile OM and perlite significantly decreased cluster-root formation in the localized layers. The OM position did not change the proportion of total cluster roots to total roots in dry biomass among no-P treatments, but more cluster roots were concentrated in the OM layers with a decreased proportion in other places. Conclusions Localized application of non-sterile OM or phytate plus OM stimulated cluster-root proliferation of L. albus in the localized layers. This effect is predominantly accounted for by P release from breakdown of OM or phytate, but not due to a change in soil density associated with OM. No evidence was found for effects of micro-organisms in OM other than those responsible for P release. PMID:20150198

A biochemical assessment of the value of top clipping nursery-grown loblolly pine seedlings

Treesearch

Shi-Jean S. Sung; Paul P. Kormanik; C.C. Black

1994-01-01

Seasonal sucrose metabolism (sucrolysis) was studied in taproot cambial tissues of nursery-grown loblolly pine seedlings to assess the value of top clipping. In sucrose-importing taproots of nonclipped seedlings, sucrose synthase (SS) was the dominant enzyme for sucrose cleavage, and its activity exhibited a distinct seasonal activity. Both root SS activity and...

A comparison of root iron reduction capabilities in Carya aquatica, Carya illinoinensis, and Carya x lecontei

USDA-ARS?s Scientific Manuscript database

Carya aquatica (water hickory), is a species that thrives in areas near water and has been shown to suffer from iron deficiency when grown outside of water-saturated soils. Carya illinoinensis (pecan), is generally iron-adequate when grown in non-flooded (i.e., non-water-saturated) areas. In water...

Benomyl Stimulates Ectomycorrhizal Development by Pisolithus Tinctorius on Shortleaf Pine Grown in Containers

Treesearch

William H. Pawuk; James P. Barnett

1981-01-01

Container-grown shortleaf pine (Pinus echinata Mill.) seedlings inoculated with Pisolithus tinctorius and drenched with benomyl formed more mycorrhizal roots than undrenched seedlings. Seedlings were drenched (2.5, 5, and 10 mg ai in 15 ml of water per individual) prior to sowing and at either 2-, 4-, or 8-week intervals....

Mapping Quantitative Trait Loci Associated with Toot Traits Using Sequencing-Based Genotyping Chromosome Segment Substitution Lines Derived from 9311 and Nipponbare in Rice (Oryza sativa L.).

PubMed

Zhou, Yong; Dong, Guichun; Tao, Yajun; Chen, Chen; Yang, Bin; Wu, Yue; Yang, Zefeng; Liang, Guohua; Wang, Baohe; Wang, Yulong

2016-01-01

Identification of quantitative trait loci (QTLs) associated with rice root morphology provides useful information for avoiding drought stress and maintaining yield production under the irrigation condition. In this study, a set of chromosome segment substitution lines derived from 9311 as the recipient and Nipponbare as donor, were used to analysis root morphology. By combining the resequencing-based bin-map with a multiple linear regression analysis, QTL identification was conducted on root number (RN), total root length (TRL), root dry weight (RDW), maximum root length (MRL), root thickness (RTH), total absorption area (TAA) and root vitality (RV), using the CSSL population grown under hydroponic conditions. A total of thirty-eight QTLs were identified: six for TRL, six for RDW, eight for the MRL, four for RTH, seven for RN, two for TAA, and five for RV. Phenotypic effect variance explained by these QTLs ranged from 2.23% to 37.08%, and four single QTLs had more than 10% phenotypic explanations on three root traits. We also detected the correlations between grain yield (GY) and root traits, and found that TRL, RTH and MRL had significantly positive correlations with GY. However, TRL, RDW and MRL had significantly positive correlations with biomass yield (BY). Several QTLs identified in our population were co-localized with some loci for grain yield or biomass. This information may be immediately exploited for improving rice water and fertilizer use efficiency for molecular breeding of root system architectures.

Carrot injury and yield response to ozone

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bennett, J.P.; Oshima, R.J.

1976-11-01

Container-grown plants of carrot (Daucus carota L.) exposed intermittently to 0.19 or 0.25 ppm ozone throughout their growth increased in plant height and total number of leaves in spite of the development of chlorotic leaves. Leaf dry weight was unaffected by ozone, but root dry matter decreased 32 to 46%. As a result, the root weight/total dry weight ration and root/shoot ratio declined significantly in the presence of ozone. A regression of root dry weight on chlorotic lead dry weight explained 35% of the root loss and predicted that 1.5 g of root tissue is lost for every g ofmore » chlorotic leaf dry weight casued by ozone injury.« less

Effect of biweekly shoot tip harvests on the growth and yield of Georgia Jet sweet potato grown hydroponically

NASA Technical Reports Server (NTRS)

Ogbuehi, Cyriacus R.; Loretan, Phil A.; Bonsi, C. K.; Hill, Walter A.; Morris, Carlton E.; Biswas, P. K.; Mortley, Desmond G.

1989-01-01

Sweet potato shoot tips have been shown to be a nutritious green vegetable. A study was conducted to determine the effect of biweekly shoot tip harvests on the growth and yield of Georgia Jet sweet potato grown in the greenhouse using the nutrient film technique (NFT). The nutrient solution consisted of a modified half Hoagland solution. Biweekly shoot tip harvests, beginning 42 days after planting, provided substantial amounts of vegetable greens and did not affect the fresh and dry foliage weights or the storage root number and fresh and dry storage root weights at final harvest. The rates of anion and cation uptake were not affected by tip harvests.

A plant culture system for producing food and recycling materials with sweetpotato in space

NASA Astrophysics Data System (ADS)

Kitaya, Yoshiaki; Yano, Sachiko; Hirai, Hiroaki

2016-07-01

The long term human life support in space is greatly dependent on the amounts of food, atmospheric O2 and clean water produced by plants. Therefore, the bio-regenerative life support system such as space farming with scheduling of crop production, obtaining high yields with a rapid turnover rate, converting atmospheric CO2 to O2 and purifying water should be established with employing suitable plant species and varieties and precisely controlling environmental variables around plants grown at a high density in a limited space. We are developing a sweetpotato culture system for producing tuberous roots as a high-calorie food and fresh edible leaves and stems as a nutritive functional vegetable food in space. In this study, we investigated the ability of food production, CO2 to O2 conversion through photosynthesis, and clean water production through transpiration in the sweetpotato production system. The biomass of edible parts in the whole plant was almost 100%. The proportion of the top (leaves and stems) and tuberous roots was strongly affected by environmental variables even when the total biomass production was mostly the same. The production of biomass and clean water was controllable especially by light, atmospheric CO2 and moisture and gas regimes in the root zone. It was confirmed that sweetpotato can be utilized for the vegetable crop as well as the root crop allowing a little waste and is a promising functional crop for supporting long-duration human activity in space.

Field-Scale Partitioning of Ecosystem Respiration Components Suggests Carbon Stabilization in a Bioenergy Grass Ecosystem

NASA Astrophysics Data System (ADS)

Black, C. K.; Miller, J. N.; Masters, M. D.; Bernacchi, C.; DeLucia, E. H.

2014-12-01

Annually-harvested agroecosystems have the potential to be net carbon sinks only if their root systems allocate sufficient carbon belowground and if this carbon is then retained as stable soil organic matter. Soil respiration measurements are the most common approach to evaluate the stability of soil carbon at experimental time scales, but valid inferences require the partitioning of soil respiration into root-derived (current-year C) and heterotrophic (older C) components. This partitioning is challenging at the field scale because roots and soil are intricately mixed and physical separation in impossible without disturbing the fluxes to be measured. To partition soil flux and estimate the C sink potential of bioenergy crops, we used the carbon isotope difference between C3 and C4 plant species to quantify respiration from roots of three C4 grasses (maize, Miscanthus, and switchgrass) grown in a site with a mixed cropping history where respiration from the breakdown of old soil carbon has a mixed C3-C4 signature. We used a Keeling plot approach to partition fluxes both at the soil surface using soil chambers and from the whole field using continuous flow sampling of air within and above the canopy. Although soil respiration rates from perennial grasses were higher than those from maize, the isotopic signature of respired carbon indicated that the fraction of soil CO2 flux attributable to current-year vegetation was 1.5 (switchgrass) to 2 (Miscanthus) times greater in perennials than that from maize, indicating that soil CO2 flux came mostly from roots and turnover of soil organic matter was reduced in the perennial crops. This reduction in soil heterotrophic respiration, combined with the much greater quantities of C allocated belowground by perennial grasses compared to maize, suggests that perennial grasses grown as bioenergy crops may be able to provide an additional climate benefit by acting as carbon sinks in addition to reducing fossil fuel consumption.

Media Effects on Lettuce Growth in "Pillows" Designed for the VEGGIE Spaceflight Growth Chamber

NASA Technical Reports Server (NTRS)

Massa, Gioia; Newsham, Gerard; McCoy, LaShelle; Stutte, Gary; Wheeler, Raymond

2012-01-01

VEGGIE is a prototype vegetable production unit for space designed by Orbital Technologies Corporation that is being developed to fly on the International Space Station. A modular plant rooting system "pillow" is being designed to support plant growth in VEGGIE under microgravity conditions. VEGGIE pillows are small self-contained packets of media with time-release fertilizer that can wick water passively from a root mat reservoir. Seeds are planted in pillows and the entire root system of a plant is contained as the crop develops, preventing loss into the spacecraft cabin. This study compared five media types and three lettuce cultivars in pillows growing in a VEGGIE analog environment.. Media consisted of a peat-based potting mix (Fafard #2,Conrad Fafard Inc., Agawam, MA), and a calcined clay, (arcillite, 1-2 mm sifted, Turface Proleague, Profile LLC, Buffalo Grove IL) as well as three different blends of the two, 70:30, 50:50, and 30:70. Lettuce cultivars tested were 'Sierra', a bi-colored French crisp Batavia lettuce, 'Outredgeous', a red romaine lettuce and 'Flandria', a green butter head variety. Plants were grown for 28 days, harvested, biometric data was obtained, and tissue mineral analysis was performed. For all cultivars, lettuce plants grown in the media blends were more productive than those in the individual media types. All cultivars showed bell-shaped curves in response to increases in arcillite / decreases in Fafard #2 for leaf area, fresh, and dry mass. Plants in 100% Fafard #2 and in 100% arcillite were stunted, but only those in higher levels of Fafard #2 (70% and 100%) had reduced shoot percent moisture, possibly indicating that mechanisms causing stunting differed. Variation in tissue nutrient content are consistent with this, with Mg and Mn highest in plants grown in 100% Fafard and decreasing as the concentration of arcillite increased. Color also varied with media, especially in the 'Sierra' lettuce, with plants grown in increasing levels of Fafard #2 being much more red and those in 100% arcillite almost completely green. The red-leaf cultivar 'Outredgeous' showed increasing chlorophyll (SPAD values) with increasing percentage of arcillite. In all cultivars tested it appears that a mixture of media types, usually 50:50 or 30:70 Fafard #2: arcillite, sustained healthier, more productive plants. Smaller, less productive plants in either of the individual media may indicate stress issues, however more work is needed to understand the reasons for this sub-optimal growth. This work was supported by NASA

Early changes in arbuscular mycorrhiza development in sugarcane under two harvest management systems.

PubMed

de Azevedo, Lucas Carvalho Basilio; Stürmer, Sidney Luiz; Lambais, Marcio Rodrigues

2014-01-01

Sugarcane (Saccharum spp.) is grown on over 8 million ha in Brazil and is used to produce ethanol and sugar. Some sugarcane fields are burned to facilitate harvesting, which can affect the soil microbial community. However, whether sugarcane pre-harvest burning affects the community of arbuscular mycorrhizal fungi (AMF) and symbioses development is not known. In this study, we investigated the early impacts of harvest management on AMF spore communities and root colonization in three sugarcane varieties, under two harvest management systems (no-burning and pre-harvest burning). Soil and root samples were collected in the field after the first harvest of sugarcane varieties SP813250, SP801842, and RB72454, and AMF species were identified based on spore morphology. Diversity indices were determined based on spore populations and root colonization determined as an indicator of symbioses development. Based on the diversity indices, spore number and species occurrence in soil, no significant differences were observed among the AMF communities, regardless of harvest management type, sugarcane variety or interactions between harvest management type and sugarcane variety. However, mycorrhiza development was stimulated in sugarcane under the no-burning management system. Our data suggest that the sugarcane harvest management system may cause early changes in arbuscular mycorrhiza development.

Early changes in arbuscular mycorrhiza development in sugarcane under two harvest management systems

PubMed Central

de Azevedo, Lucas Carvalho Basilio; Stürmer, Sidney Luiz; Lambais, Marcio Rodrigues

2014-01-01

Sugarcane (Saccharum spp.) is grown on over 8 million ha in Brazil and is used to produce ethanol and sugar. Some sugarcane fields are burned to facilitate harvesting, which can affect the soil microbial community. However, whether sugarcane pre-harvest burning affects the community of arbuscular mycorrhizal fungi (AMF) and symbioses development is not known. In this study, we investigated the early impacts of harvest management on AMF spore communities and root colonization in three sugarcane varieties, under two harvest management systems (no-burning and pre-harvest burning). Soil and root samples were collected in the field after the first harvest of sugarcane varieties SP813250, SP801842, and RB72454, and AMF species were identified based on spore morphology. Diversity indices were determined based on spore populations and root colonization determined as an indicator of symbioses development. Based on the diversity indices, spore number and species occurrence in soil, no significant differences were observed among the AMF communities, regardless of harvest management type, sugarcane variety or interactions between harvest management type and sugarcane variety. However, mycorrhiza development was stimulated in sugarcane under the no-burning management system. Our data suggest that the sugarcane harvest management system may cause early changes in arbuscular mycorrhiza development. PMID:25477936

The biocontrol endophytic bacterium Pseudomonas fluorescens PICF7 induces systemic defense responses in aerial tissues upon colonization of olive roots.

PubMed

Gómez-Lama Cabanás, Carmen; Schilirò, Elisabetta; Valverde-Corredor, Antonio; Mercado-Blanco, Jesús

2014-01-01

Pseudomonas fluorescens PICF7, a native olive root endophyte and effective biocontrol agent (BCA) against Verticillium wilt of olive, is able to trigger a broad range of defense responses in root tissues of this woody plant. In order to elucidate whether strain PICF7 also induces systemic defense responses in above-ground organs, aerial tissues of olive plants grown under non-gnotobiotic conditions were collected at different time points after root bacterization with this endophytic BCA. A suppression subtractive hybridization (SSH) cDNA library, enriched in up-regulated genes, was generated. This strategy enabled the identification of 376 ESTs (99 contigs and 277 singlets), many of them related to response to different stresses. Five ESTs, involved in defense responses, were selected to carry out time-course quantitative real-time PCR (qRT-PCR) experiments aiming to: (1) validate the induction of these genes, and (2) shed light on their expression pattern along time (from 1 to 15 days). Induction of olive genes potentially coding for lipoxygenase 2, catalase, 1-aminocyclopropane-1-carboxylate oxidase, and phenylananine ammonia-lyase was thus confirmed at some time points. Computational analysis also revealed that different transcription factors were up-regulated in olive aerial tissues (i.e., JERF, bHLH, WRKY), as previously reported for roots. Results confirmed that root colonization by this endophytic bacterium does not only trigger defense responses in this organ but also mounts a wide array of systemic defense responses in distant tissues (stems, leaves). This sheds light on how olive plants respond to the "non-hostile" colonization by a bacterial endophyte and how induced defense response can contribute to the biocontrol activity of strain PICF7.

The biocontrol endophytic bacterium Pseudomonas fluorescens PICF7 induces systemic defense responses in aerial tissues upon colonization of olive roots

PubMed Central

Gómez-Lama Cabanás, Carmen; Schilirò, Elisabetta; Valverde-Corredor, Antonio; Mercado-Blanco, Jesús

2014-01-01

Pseudomonas fluorescens PICF7, a native olive root endophyte and effective biocontrol agent (BCA) against Verticillium wilt of olive, is able to trigger a broad range of defense responses in root tissues of this woody plant. In order to elucidate whether strain PICF7 also induces systemic defense responses in above-ground organs, aerial tissues of olive plants grown under non-gnotobiotic conditions were collected at different time points after root bacterization with this endophytic BCA. A suppression subtractive hybridization (SSH) cDNA library, enriched in up-regulated genes, was generated. This strategy enabled the identification of 376 ESTs (99 contigs and 277 singlets), many of them related to response to different stresses. Five ESTs, involved in defense responses, were selected to carry out time-course quantitative real-time PCR (qRT-PCR) experiments aiming to: (1) validate the induction of these genes, and (2) shed light on their expression pattern along time (from 1 to 15 days). Induction of olive genes potentially coding for lipoxygenase 2, catalase, 1-aminocyclopropane-1-carboxylate oxidase, and phenylananine ammonia-lyase was thus confirmed at some time points. Computational analysis also revealed that different transcription factors were up-regulated in olive aerial tissues (i.e., JERF, bHLH, WRKY), as previously reported for roots. Results confirmed that root colonization by this endophytic bacterium does not only trigger defense responses in this organ but also mounts a wide array of systemic defense responses in distant tissues (stems, leaves). This sheds light on how olive plants respond to the “non-hostile” colonization by a bacterial endophyte and how induced defense response can contribute to the biocontrol activity of strain PICF7. PMID:25250017

The host plant Pinus pinaster exerts specific effects on phosphate efflux and polyphosphate metabolism of the ectomycorrhizal fungus Hebeloma cylindrosporum: a radiotracer, cytological staining and 31 P NMR spectroscopy study.

PubMed

Torres-Aquino, Margarita; Becquer, Adeline; Le Guernevé, Christine; Louche, Julien; Amenc, Laurie K; Staunton, Siobhan; Quiquampoix, Hervé; Plassard, Claude

2017-02-01

Ectomycorrhizal (ECM) association can improve plant phosphorus (P) nutrition. Polyphosphates (polyP) synthesized in distant fungal cells after P uptake may contribute to P supply from the fungus to the host plant if they are hydrolyzed to phosphate in ECM roots then transferred to the host plant when required. In this study, we addressed this hypothesis for the ECM fungus Hebeloma cylindrosporum grown in vitro and incubated without plant or with host (Pinus pinaster) and non-host (Zea mays) plants, using an experimental system simulating the symbiotic interface. We used 32 P labelling to quantify P accumulation and P efflux and in vivo and in vitro nuclear magnetic resonance (NMR) spectroscopy and cytological staining to follow the fate of fungal polyP. Phosphate supply triggered a massive P accumulation as newly synthesized long-chain polyP in H. cylindrosporum if previously grown under P-deficient conditions. P efflux from H. cylindrosporum towards the roots was stimulated by both host and non-host plants. However, the host plant enhanced 32 P release compared with the non-host plant and specifically increased the proportion of short-chain polyP in the interacting mycelia. These results support the existence of specific host plant effects on fungal P metabolism able to provide P in the apoplast of ectomycorrhizal roots. © 2016 John Wiley & Sons Ltd.

Uptake of perfluorinated alkyl acids by hydroponically grown lettuce (Lactuca sativa).

PubMed

Felizeter, Sebastian; McLachlan, Michael S; de Voogt, Pim

2012-11-06

An uptake study was carried out to assess the potential human exposure to perfluorinated alkyl acids (PFAAs) through the ingestion of vegetables. Lettuce (Lactuca sativa) was grown in PFAA-spiked nutrient solutions at four different concentrations, ranging from 10 ng/L to 10 μg/L. Eleven perfluorinated carboxylic acids (PFCAs) and three perfluorinated sulfonic acids (PFSAs) were analyzed by HPLC-MS/MS. At the end of the experiment, the major part of the total mass of each of the PFAAs (except the short-chain, C4-C7, PFCAs) taken up by plants appeared to be retained in the nonedible part, viz. the roots. Root concentration factors (RCF), foliage/root concentration factors (FRCF), and transpiration stream concentration factors (TSCF) were calculated. For the long chained PFAAs, RCF values were highest, whereas FRCF were lowest. This indicates that uptake by roots is likely governed by sorption of PFAAs to lipid-rich root solids. Translocation from roots to shoots is restricted and highly depending on the hydrophobicity of the compounds. Although the TSCF show that longer-chain PFCAs (e.g., perfluorododecanoic acid) get better transferred from the nutrient solution to the foliage than shorter-chain PFCAs (e.g., perfluoroheptanoic acid), the major fraction of longer-chain PFCAs is found in roots due to additional adsorption from the spiked solution. Due to the strong electron-withdrawing effect of the fluorine atoms the role of the negative charge of the dissociated PFAAs is likely insignificant.

High-resolution quantification of root dynamics in split-nutrient rhizoslides reveals rapid and strong proliferation of maize roots in response to local high nitrogen

PubMed Central

in ‘t Zandt, Dina; Le Marié, Chantal; Kirchgessner, Norbert; Visser, Eric J.W.; Hund, Andreas

2015-01-01

The plant’s root system is highly plastic, and can respond to environmental stimuli such as high nitrogen (N) in patches. A root may respond to an N patch by selective placement of new lateral roots, and therewith increases root N uptake. This may be a desirable trait in breeding programmes, since it decreases NO3 - leaching and N2O emission. Roots of maize (Zea mays L.) were grown without N in split-nutrient rhizoslides. One side of the slides was exposed to high N after 15 d of root development, and root elongation was measured for another 15 d, described in a time course model and parameterized. The elongation rates of crown axile roots on the N-treated side of the plant followed a logistic increase to a maximum of 5.3cm d-1; 95% of the maximum were reached within 4 d. At the same time, on the untreated side, axile root elongation dropped linearly to 1.2cm d-1 within 6.4 d and stayed constant thereafter. Twice as many lateral roots were formed on the crown axis on the N side compared to the untreated side. Most strikingly, the elongation rates of laterals of the N side increased linearly with most of the roots reaching an asymptote ~8 d after start of the N treatment. By contrast, laterals on the side without N did not show any detectable elongation beyond the first day after their emergence. We conclude that split-nutrient rhizoslides have great potential to improve our knowledge about nitrogen responsiveness and selection for contrasting genotypes. PMID:26105997

Rapid changes in protein phosphorylation associated with light-induced gravity perception in corn roots

NASA Technical Reports Server (NTRS)

McFadden, J. J.; Poovaiah, B. W.

1988-01-01

The effect of light and calcium depletion on in vivo protein phosphorylation was tested using dark-grown roots of Merit corn. Light caused rapid and specific promotion of phosphorylation of three polypeptides. Pretreatment of roots with ethylene glycol bis N,N,N',N' tetraacetic acid and A23187 prevented light-induced changes in protein phosphorylation. We postulate that these changes in protein phosphorylation are involved in the light-induced gravity response.

Bacteria in combination with fertilizers promote root and shoot growth of maize in saline-sodic soil.

PubMed

Zafar-Ul-Hye, Muhammad; Farooq, Hafiz Muhammad; Hussain, Mubshar

2015-03-01

Salinity is the leading abiotic stress hampering maize ( Zea mays L.) growth throughout the world, especially in Pakistan. During salinity stress, the endogenous ethylene level in plants increases, which retards proper root growth and consequent shoot growth of the plants. However, certain bacteria contain the enzyme 1-aminocyclopropane-1-carboxylate (ACC) deaminase, which converts 1-aminocyclopropane-1-carboxylic acid (an immediate precursor of ethylene biosynthesis in higher plants) into ammonia and α-ketobutyrate instead of ethylene. In the present study, two Pseudomonas bacterial strains containing ACC-deaminase were tested separately and in combinations with mineral fertilizers to determine their potential to minimize/undo the effects of salinity on maize plants grown under saline-sodic field conditions. The data recorded at 30, 50 and 70 days after sowing revealed that both the Pseudomonas bacterial strains improved root and shoot length, root and shoot fresh weight, and root and shoot dry weight up to 34, 43, 35, 71, 55 and 68%, respectively, when applied without chemical fertilizers: these parameter were enhanced up to 108, 95, 100, 131, 100 and 198%, respectively, when the strains were applied along with chemical fertilizers. It can be concluded that ACC-deaminase Pseudomonas bacterial strains applied alone and in conjunction with mineral fertilizers improved the root and shoot growth of maize seedlings grown in saline-sodic soil.

Bacteria in combination with fertilizers promote root and shoot growth of maize in saline-sodic soil

PubMed Central

Zafar-ul-Hye, Muhammad; Farooq, Hafiz Muhammad; Hussain, Mubshar

2015-01-01

Salinity is the leading abiotic stress hampering maize ( Zea mays L.) growth throughout the world, especially in Pakistan. During salinity stress, the endogenous ethylene level in plants increases, which retards proper root growth and consequent shoot growth of the plants. However, certain bacteria contain the enzyme 1-aminocyclopropane-1-carboxylate (ACC) deaminase, which converts 1-aminocyclopropane-1-carboxylic acid (an immediate precursor of ethylene biosynthesis in higher plants) into ammonia and α-ketobutyrate instead of ethylene. In the present study, two Pseudomonas bacterial strains containing ACC-deaminase were tested separately and in combinations with mineral fertilizers to determine their potential to minimize/undo the effects of salinity on maize plants grown under saline-sodic field conditions. The data recorded at 30, 50 and 70 days after sowing revealed that both the Pseudomonas bacterial strains improved root and shoot length, root and shoot fresh weight, and root and shoot dry weight up to 34, 43, 35, 71, 55 and 68%, respectively, when applied without chemical fertilizers: these parameter were enhanced up to 108, 95, 100, 131, 100 and 198%, respectively, when the strains were applied along with chemical fertilizers. It can be concluded that ACC-deaminase Pseudomonas bacterial strains applied alone and in conjunction with mineral fertilizers improved the root and shoot growth of maize seedlings grown in saline-sodic soil. PMID:26221093

Not a load of rubbish: simulated field trials in large-scale containers.

PubMed

Hohmann, M; Stahl, A; Rudloff, J; Wittkop, B; Snowdon, R J

2016-09-01

Assessment of yield performance under fluctuating environmental conditions is a major aim of crop breeders. Unfortunately, results from controlled-environment evaluations of complex agronomic traits rarely translate to field performance. A major cause is that crops grown over their complete lifecycle in a greenhouse or growth chamber are generally constricted in their root growth, which influences their response to important abiotic constraints like water or nutrient availability. To overcome this poor transferability, we established a plant growth system comprising large refuse containers (120 L 'wheelie bins') that allow detailed phenotyping of small field-crop populations under semi-controlled growth conditions. Diverse winter oilseed rape cultivars were grown at field densities throughout the crop lifecycle, in different experiments over 2 years, to compare seed yields from individual containers to plot yields from multi-environment field trials. We found that we were able to predict yields in the field with high accuracy from container-grown plants. The container system proved suitable for detailed studies of stress response physiology and performance in pre-breeding populations. Investment in automated large-container systems may help breeders improve field transferability of greenhouse experiments, enabling screening of pre-breeding materials for abiotic stress response traits with a positive influence on yield. © 2016 John Wiley & Sons Ltd.

Mevalonate kinase activity during different stages of plant regeneration from nodular callus cultures in white pine (Pinus strobus).

PubMed

Tang, Wei; Newton, Ronald J

2006-02-01

Mevalonate kinase (MK) catalyzes a step in the isoprenoid biosynthetic pathway, which leads to a huge number of compounds that play important roles in plant growth and development. Here, we report on changes in MK activity in white pine (Pinus strobus L.) during plant regeneration by adventitious shoot organogenesis from cotyledons of mature embryos, including nodular callus induction, shoot formation and rooting. Nodular calli were induced from Pinus strobus (PS) embryos by culture in nodular callus induction medium in a 0-, 8- or 16-h photoperiod. Mevalonate kinase activity peaked in nodular calli after three weeks of culture on nodular callus induction medium in a 16-h photoperiod, whereas frequency of nodular callus formation peaked after 4 weeks of culture on nodular callus induction medium in darkness. During adventitious shoot formation, MK activity peaked in shoots derived from dark-grown nodular calli after 3 weeks on bud formation medium, and frequency of shoot formation was highest in dark-grown nodular calli cultured on bud formation medium for 4 weeks. During rooting, MK activity peaked 2 weeks after transfer of adventitious shoots to rooting medium and rooting frequency was highest in adventitious shoots after 3 weeks on rooting medium. Although during nodular callus induction in darkness MK activity was inversely related to frequency of nodular callus formation, MK activity was highly correlated with frequency of shoot formation and with rooting frequency. The observed increase in MK activity preceding rooting suggests that MK could serve as a marker for rooting of white pine shoots in vitro.

Root foraging elicits niche complementarity-dependent yield advantage in the ancient ‘three sisters’ (maize/bean/squash) polyculture

PubMed Central

Zhang, Chaochun; Postma, Johannes A.; York, Larry M.; Lynch, Jonathan P.

2014-01-01

Background and Aims Since ancient times in the Americas, maize, bean and squash have been grown together in a polyculture known as the ‘three sisters’. This polyculture and its maize/bean variant have greater yield than component monocultures on a land-equivalent basis. This study shows that below-ground niche complementarity may contribute to this yield advantage. Methods Monocultures and polycultures of maize, bean and squash were grown in two seasons in field plots differing in nitrogen (N) and phosphorus (P) availability. Root growth patterns of individual crops and entire polycultures were determined using a modified DNA-based technique to discriminate roots of different species. Key Results The maize/bean/squash and maize/bean polycultures had greater yield and biomass production on a land-equivalent basis than the monocultures. Increased biomass production was largely caused by a complementarity effect rather than a selection effect. The differences in root crown architecture and vertical root distribution among the components of the ‘three sisters’ suggest that these species have different, possibly complementary, nutrient foraging strategies. Maize foraged relatively shallower, common bean explored the vertical soil profile more equally, while the root placement of squash depended on P availability. The density of lateral root branching was significantly greater for all species in the polycultures than in the monocultures. Conclusions It is concluded that species differences in root foraging strategies increase total soil exploration, with consequent positive effects on the growth and yield of these ancient polycultures. PMID:25274551

Monitoring the colonization of sugarcane and rice plants by the endophytic diazotrophic bacterium Gluconacetobacter diazotrophicus marked with gfp and gusA reporter genes.

PubMed

Rouws, L F M; Meneses, C H S G; Guedes, H V; Vidal, M S; Baldani, J I; Schwab, S

2010-09-01

To evaluate the colonization process of sugarcane plantlets and hydroponically grown rice seedlings by Gluconacetobacter diazotrophicus strain PAL5 marked with the gusA and gfp reporter genes. Sugarcane plantlets inoculated in vitro with PAL5 carrying the gfp::gusA plasmid pHRGFPGUS did not present green fluorescence, but beta-glucuronidase (GUS)-stained bacteria could be observed inside sugarcane roots. To complement this existing inoculation methodology for micropropagated sugarcane with a more rapid colonization assay, we employed hydroponically grown gnotobiotic rice seedlings to study PAL5-plant interaction. PAL5 could be isolated from the root surface (10(8) CFU g(-1)) and from surface-disinfected root and stem tissues (10(4) CFU g(-1)) of inoculated plants, suggesting that PAL5 colonized the internal plant tissues. Light microscopy confirmed the presence of bacteria inside the root tissue. After inoculation of rice plantlets with PAL5 marked with the gfp plasmid pHRGFPTC, bright green fluorescent bacteria could be seen colonizing the rice root surface, mainly at the sites of lateral root emergence, at root caps and on root hairs. The plasmids pHRGFPGUS and pHRGFPTC are valid tools to mark PAL5 and monitor the colonization of micropropagated sugarcane and hydroponic rice seedlings. These tools are of use to: (i) study PAL5 mutants affected in bacteria-plant interactions, (ii) monitor plant colonization in real time and (iii) distinguish PAL5 from other bacteria during the study of mixed inoculants.

Free-air CO2 enrichment (FACE) reduces the inhibitory effect of soil nitrate on N2 fixation of Pisum sativum.

PubMed

Butterly, Clayton R; Armstrong, Roger; Chen, Deli; Tang, Caixian

2016-01-01

Additional carbohydrate supply resulting from enhanced photosynthesis under predicted future elevated CO2 is likely to increase symbiotic nitrogen (N) fixation in legumes. This study examined the interactive effects of atmospheric CO2 and nitrate (NO3(-)) concentration on the growth, nodulation and N fixation of field pea (Pisum sativum) in a semi-arid cropping system. Field pea was grown for 15 weeks in a Vertosol containing 5, 25, 50 or 90 mg NO3(-)-N kg(-1) under either ambient CO2 (aCO2; 390 ppm) or elevated CO2 (eCO2; 550 ppm) using free-air CO2 enrichment (SoilFACE). Under aCO2, field pea biomass was significantly lower at 5 mg NO3(-)-N kg(-1) than at 90 mg NO3(-)-N kg(-1) soil. However, increasing the soil N level significantly reduced nodulation of lateral roots but not the primary root, and nodules were significantly smaller, with 85% less nodule mass in the 90 NO3(-)-N kg(-1) than in the 5 mg NO3(-)-N kg(-1) treatment, highlighting the inhibitory effects of NO3(-). Field pea grown under eCO2 had greater biomass (approx. 30%) than those grown under aCO2, and was not affected by N level. Overall, the inhibitory effects of NO3(-) on nodulation and nodule mass appeared to be reduced under eCO2 compared with aCO2, although the effects of CO2 on root growth were not significant. Elevated CO2 alleviated the inhibitory effect of soil NO3(-) on nodulation and N2 fixation and is likely to lead to greater total N content of field pea growing under future elevated CO2 environments. © The Author 2015. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

In situ measurements of root exudation in three hardwood species in southern Indiana

NASA Astrophysics Data System (ADS)

O'Connor, D. A.; Brzostek, E. R.; Fisher, J. B.; Phillips, R.

2012-12-01

Root exudation - the release of soluble organic compounds to soil - has long been considered a black box in ecology owing to methodological difficulties associated with measuring this flux in situ. This knowledge gap is significant given recent findings that suggest exudate inputs are appreciable in magnitude (2-5% of net primary production) and are coupled to microbial activities, nutrient release and soil organic matter decomposition. We developed a novel experimental system for collecting exudates from intact roots of field-grown trees using cuvettes filled with sterile glass beads. We measured root exudation for three tree species in ~80 year old mixed hardwood forest in south central Indiana, USA in the summer of 2012. Exudation rates varied from 0 to 1413 ug C/g root/day, and differed by sampling date and among trees species. Overall, rates were greater in early relative to late July, and greater in sugar maple (Acer saccharum) and white oak (Quercus alba) relative to tulip poplar (Liriodendron tulipifera). Across all species, exudation rates were correlated with root mass, indicating that greater allocation to roots likely increases the amount of C available to fuel soil microbial activity. Collectively, the results of this study should enable us to develop improved model parameterizations of the C costs associated with nutrient acquisition, an important feedback for predicting the role of vegetation in mediating climate change.

Comparison between Arabidopsis and Rice for Main Pathways of K(+) and Na(+) Uptake by Roots.

PubMed

Nieves-Cordones, Manuel; Martínez, Vicente; Benito, Begoña; Rubio, Francisco

2016-01-01

K(+) is an essential macronutrient for plants. It is acquired by specific uptake systems located in roots. Although the concentrations of K(+) in the soil solution are widely variable, K(+) nutrition is secured by uptake systems that exhibit different affinities for K(+). Two main systems have been described for root K(+) uptake in several species: the high-affinity HAK5-like transporter and the inward-rectifier AKT1-like channel. Other unidentified systems may be also involved in root K(+) uptake, although they only seem to operate when K(+) is not limiting. The use of knock-out lines has allowed demonstrating their role in root K(+) uptake in Arabidopsis and rice. Plant adaptation to the different K(+) supplies relies on the finely tuned regulation of these systems. Low K(+)-induced transcriptional up-regulation of the genes encoding HAK5-like transporters occurs through a signal cascade that includes changes in the membrane potential of root cells and increases in ethylene and reactive oxygen species concentrations. Activation of AKT1 channels occurs through phosphorylation by the CIPK23/CBL1 complex. Recently, activation of the Arabidopsis HAK5 by the same complex has been reported, pointing to CIPK23/CBL as a central regulator of the plant's adaptation to low K(+). Na(+) is not an essential plant nutrient but it may be beneficial for some plants. At low concentrations, Na(+) improves growth, especially under K(+) deficiency. Thus, high-affinity Na(+) uptake systems have been described that belong to the HKT and HAK families of transporters. At high concentrations, typical of saline environments, Na(+) accumulates in plant tissues at high concentrations, producing alterations that include toxicity, water deficit and K(+) deficiency. Data concerning pathways for Na(+) uptake into roots under saline conditions are still scarce, although several possibilities have been proposed. The apoplast is a significant pathway for Na(+) uptake in rice grown under salinity conditions, but in other plant species different mechanisms involving non-selective cation channels or transporters are under discussion.

Comparison between Arabidopsis and Rice for Main Pathways of K+ and Na+ Uptake by Roots

PubMed Central

Nieves-Cordones, Manuel; Martínez, Vicente; Benito, Begoña; Rubio, Francisco

2016-01-01

K+ is an essential macronutrient for plants. It is acquired by specific uptake systems located in roots. Although the concentrations of K+ in the soil solution are widely variable, K+ nutrition is secured by uptake systems that exhibit different affinities for K+. Two main systems have been described for root K+ uptake in several species: the high-affinity HAK5-like transporter and the inward-rectifier AKT1-like channel. Other unidentified systems may be also involved in root K+ uptake, although they only seem to operate when K+ is not limiting. The use of knock-out lines has allowed demonstrating their role in root K+ uptake in Arabidopsis and rice. Plant adaptation to the different K+ supplies relies on the finely tuned regulation of these systems. Low K+-induced transcriptional up-regulation of the genes encoding HAK5-like transporters occurs through a signal cascade that includes changes in the membrane potential of root cells and increases in ethylene and reactive oxygen species concentrations. Activation of AKT1 channels occurs through phosphorylation by the CIPK23/CBL1 complex. Recently, activation of the Arabidopsis HAK5 by the same complex has been reported, pointing to CIPK23/CBL as a central regulator of the plant’s adaptation to low K+. Na+ is not an essential plant nutrient but it may be beneficial for some plants. At low concentrations, Na+ improves growth, especially under K+ deficiency. Thus, high-affinity Na+ uptake systems have been described that belong to the HKT and HAK families of transporters. At high concentrations, typical of saline environments, Na+ accumulates in plant tissues at high concentrations, producing alterations that include toxicity, water deficit and K+ deficiency. Data concerning pathways for Na+ uptake into roots under saline conditions are still scarce, although several possibilities have been proposed. The apoplast is a significant pathway for Na+ uptake in rice grown under salinity conditions, but in other plant species different mechanisms involving non-selective cation channels or transporters are under discussion. PMID:27458473

Developing and demonstrating low-energy climate control and production techniques for greenhouse-grown citrus and ornamental crops

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bodnaruk, W.H. Jr.

1983-04-01

The aim of this study was to develop and demonstrate low energy climate control and production techniques for greenhouse grown citrus and ornamental crops. Emphasis was placed on design, fuel efficiency and plant response to warm water soil heating systems using solar energy and LP gas. An energy requirement of 28Btus output per hour per square foot of bed space will provide soil temperature of 70/sup 0/F minimum when air temperatures are maintained at 60/sup 0/F. Soil heating to 70/sup 0/ increased rooting and growth of 8 foliage plant varieties by 25 to 45% compared to plants grown under 60/supmore » 0/F air temperature conditions. Providing soil heating, however, increased fuel consumption in the central Florida test facilities by 30% in the winters of 1980-81 and 1981-82. Solar tie-in to soil heating systems has the potential of reducing fuel usage. Solar heated water provided 4 hours of soil heating following a good collection day. Decreased in-bed pipe spacing and increased storage capacity should increase the solar percentage to 6 hours.« less

Measuring and modeling three-dimensional water uptake of a growing faba bean (Vicia faba) within a soil column

NASA Astrophysics Data System (ADS)

Huber, Katrin; Koebernick, Nicolai; Kerkhofs, Elien; Vanderborght, Jan; Javaux, Mathieu; Vetterlein, Doris; Vereecken, Harry

2014-05-01

A faba bean was grown in a column filled with a sandy soil, which was initially close to saturation and then subjected to a single drying cycle of 30 days. The column was divided in four hydraulically separated compartments using horizontal paraffin layers. Paraffin is impermeable to water but penetrable by roots. Thus by growing deeper, the roots can reach compartments that still contain water. The root architecture was measured every second day by X-ray CT. Transpiration rate, soil matric potential in four different depths, and leaf area were measured continously during the experiment. To investigate the influence of the partitioning of available soil water in the soil column on water uptake, we used R-SWMS, a fully coupled root and soil water model [1]. We compared a scenario with and without the split layers and investigated the influence on root xylem pressure. The detailed three-dimensional root architecture was obtained by reconstructing binarized root images manually with a virtual reality system, located at the Juelich Supercomputing Centre [2]. To verify the properties of the root system, we compared total root lengths, root length density distributions and root surface with estimations derived from Minkowski functionals [3]. In a next step, knowing the change of root architecture in time, we could allocate an age to each root segment and use this information to define age dependent root hydraulic properties that are required to simulate water uptake for the growing root system. The scenario with the split layers showed locally much lower pressures than the scenario without splits. Redistribution of water within the unrestricted soil column led to a more uniform distribution of water uptake and lowers the water stress in the plant. However, comparison of simulated and measured pressure heads with tensiometers suggested that the paraffin layers were not perfectly hydraulically isolating the different soil layers. We could show compensation efficiency of water uptake by the roots in the lower and wetter compartments. By comparing transpiration rates of experiments with and without additional paraffin layers, we were able to quantify restrictions of plant growth to available soil water. [1] Javaux, M., T. Schröder, J. Vanderborght, and H. Vereecken (2008), Use of a Three-Dimensional Detailed Modeling Approach for Predicting Root Water Uptake, Vadose Zone Journal, 7(3), 1079-1079. [2] Stingaciu, L., H. Schulz, A. Pohlmeier, S. Behnke, H. Zilken, M. Javaux, H. Vereecken (2013), In Situ Root System Architecture Extraction from Magnetic Resonance Imaging for Water Uptake Modeling, Vadose Zone Journal, 12(1). [3] Koebernick, N., U. Weller, K. Huber, S. Schlüter, H.-J. Vogel, R. Jahn; H. Vereecken, D. Vetterlein, In situ visualisation and quantification of root-system architecture and growth with X-ray CT, Manuscript submitted for publication.

Identifying root exudates in field contaminated soil systems

NASA Astrophysics Data System (ADS)

Rosenfeld, C.; Martinez, C. E.

2012-12-01

Carbon (C) compounds exuded from plant roots comprise a significant and reactive fraction of belowground C pools. These exudates substantially alter the soil directly surrounding plant roots and play a vital role in the global C cycle, soil ecology, and ecosystem mobility of both nutrients and contaminants. In soils, the solubility and bioavailability of metals such as iron, zinc, and cadmium are intricately linked to the quantity and chemical characteristics of the C compounds allocated to the soil by plants. Cadmium (Cd), a toxic heavy metal, forms stronger bonds with reduced S- and N-containing compounds than with carboxylic acids, which may influence exudate composition in hyperaccumulator and tolerant plants grown in Cd contaminated soils. We hypothesize that hyperaccumulator plants will exude a larger quantity of aromatic N and chelating di- and tri-carboxylic acid molecules, while plants that exclude heavy metals from uptake will exude a larger proportion of reduced S containing molecules. This study examines how a variety of techniques can measure the low concentrations of complex organic mixtures exuded by hyperaccumulator and non-hyperaccumulator plants grown in Cd-contaminated soils. Two congeneric plants, Thlaspi caerulescens (Ganges ecotype), and T. caerulescens (Prayon ecotype) were grown in 0.5 kg pots filled with Cd-contaminated field soils from Chicago, IL. Field soils were contaminated as a result of the application of contaminated biosolids in the 1960's and 1970's. Pots were fitted for rhizon soil moisture samplers, micro-lysimeters developed for in situ collection of small volumes in unsaturated soils, prior to planting. Plants were grown for 8 weeks before exudate collection. After the 8 weeks of growth, a pulse-chase isotope tracer method using the C stable isotope, 13C, was employed to differentiate plant-derived compounds from background soil and microbial-derived compounds. Plants were placed in a CO2 impermeable chamber, and the soil surface was covered by CO2 impermeable sheets to ensure that all 13C in the soil results from photoassimilated C released by roots and not soil-atmosphere gas exchange. Ambient CO2 was drawn down in the system until the CO2 concentration within the tent was less than 50 ppm, after which the labeled 13CO2 was introduced, returning the CO2 concentration to the ambient level (~375 ppm). The CO2 pulse lasted for 60 minutes to allow enough time for 13C assimilation within the plants. In order to determine the ideal sampling time, soil pore water samples were extracted every 1-2 hours following the 13C pulse application, over the course of 24 hours. Samples were analyzed for delta 13C as well as %C, and results indicate that the greatest plant-derived dissolved organic C is present at about 6 hours following the 13C pulse. A second experiment will also be conducted using a combination of NMR and mass spectrometry methods to obtain detailed information regarding chemical structures within exudate samples.

Bacterial physiological diversity in the rhizosphere of range plants in response to retorted shale stress. [Agropyron smithii Rydb; Atriplex canescens (Pursh) Nutt

DOE Office of Scientific and Technical Information (OSTI.GOV)

Metzger, W.C.; Klein, D.A.; Redente, E.F.

1986-10-01

Bacterial populations were isolated from the soil-root interface and root-free regions of Agropyron smithii Rydb. and Atriplex canescens (Pursh) Nutt. grown in soil, retorted shale, or soil over shale. Bacteria isolated from retorted shale exhibited a wider range of tolerance to alkalinity and salinity and decreased growth on amino acid substrates compared with bacteria from soil and soil-over-shale environments. Exoenzyme production was only slightly affected by growth medium treatment. Viable bacterial populations were higher in the rhizosphere and rhizoplane of plants grown in retorted shale than in plants grown in soil or soil over shale. In addition, a greater numbermore » of physiological groups of rhizosphere bacteria was observed in retorted shale, compared with soil alone. Two patterns of community similarity were observed in comparisons of bacteria from soil over shale with those from soil and retorted-shale environments. Root-associated populations from soil over shale had a higher proportion of physiological groups in common with those from the soil control than those from the retorted-shale treatment. However, in non-rhizosphere populations, bacterial groups from soil over shale more closely resembled the physiological groups from retorted shale.« less

Association of plant growth-promoting Serratia spp. with the root nodules of chickpea.

PubMed

Zaheer, Ahmad; Mirza, Babur S; Mclean, Joan E; Yasmin, Sumera; Shah, Tariq Mahmud; Malik, Kauser A; Mirza, M Sajjad

2016-01-01

Serratia species-affiliated DNA sequences have recently been discovered in the root nodules of two chickpea cultivars; however, little is known about their potential influence on chickpea plant growth. All Serratia-affiliated sequences (1136) could be grouped into two clusters at 98% DNA similarity. The major cluster, represented by 96% of sequences, was closely associated with Serratia marcescens sequences from GenBank. In the current study, we isolated two Serratia strains, 5D and RTL100, from root nodules of a field-grown Desi cultivar from Faisalabad and Thal areas, respectively. In vitro, strain 5D showed significantly higher phosphate (P) solubilization and lactic acid production than RTL100, whereas a comparable concentration of phytohormone was produced by both isolates. The application of Serratia strain 5D as an inoculum resulted in 25.55% and 30.85% increases in the grain yield of crops grown on fertile soil in irrigated areas and nutrient-deficient soil in rainfed areas, respectively, compared to the non-inoculated control. Results of plant inoculations indicated that Serratia sp. 5D and RTL100 can serve as effective microbial inoculants, particularly in nutrient-deficient soils in rainfed areas, where chickpea is the only major crop grown during the entire year. Copyright © 2016 Institut Pasteur. All rights reserved.

The effect of limited availability of N or water on C allocation to fine roots and annual fine root turnover in Alnus incana and Salix viminalis.

PubMed

Rytter, Rose-Marie

2013-09-01

The effect of limited nitrogen (N) or water availability on fine root growth and turnover was examined in two deciduous species, Alnus incana L. and Salix viminalis L., grown under three different regimes: (i) supply of N and water in amounts which would not hamper growth, (ii) limited N supply and (iii) limited water supply. Plants were grown outdoors during three seasons in covered and buried lysimeters placed in a stand structure and filled with quartz sand. Computer-controlled irrigation and fertilization were supplied through drip tubes. Production and turnover of fine roots were estimated by combining minirhizotron observations and core sampling, or by sequential core sampling. Annual turnover rates of fine roots <1 mm (5-6 year(-1)) and 1-2 mm (0.9-2.8 year(-1)) were not affected by changes in N or water availability. Fine root production (<1 mm) differed between Alnus and Salix, and between treatments in Salix; i.e., absolute length and biomass production increased in the order: water limited < unlimited < N limited. Few treatment effects were detected for fine roots 1-2 mm. Proportionally more C was allocated to fine roots (≤2 mm) in N or water-limited Salix; 2.7 and 2.3 times the allocation to fine roots in the unlimited regime, respectively. Estimated input to soil organic carbon increased by ca. 20% at N limitation in Salix. However, future studies on fine root decomposition under various environmental conditions are required. Fine root growth responses to N or water limitation were less pronounced in Alnus, thus indicating species differences caused by N-fixing capacity and slower initial growth in Alnus, or higher fine root plasticity in Salix. A similar seasonal growth pattern across species and treatments suggested the influence of outer stimuli, such as temperature and light.

The effect of iron plaque on uptake and translocation of norfloxacin in rice seedlings grown in paddy soil.

PubMed

Yan, Dafang; Ma, Wei; Song, Xiaojing; Bao, Yanyu

2017-03-01

Although the role of iron plaque on rice root surface has been investigated in recent years, its effect on antibiotic uptake remains uncertain. In the study, pot experiment was conducted to investigate the effect of iron plaque on uptake and translocation of norfloxacin (adding 10 and 50 mg·kg -1 treatments) in rice seedlings grown in paddy soil. Iron plaque was induced by adding different amounts of Fe(II) in soil. The results showed that the presence of norfloxacin can decrease the amount of iron plaque induced. After rice with iron plaque induced, norfloxacin was mainly accumulated in iron plaque on root surface, followed by inside root, but its translocation from root to other rice tissues is not observed. Iron plaque played the role of a barrier for norfloxacin uptake into rice roots under high norfloxacin concentration of 50 mg·kg -1 , however not that under low concentration of 10 mg·kg -1 . And the barrier function was the most strongest with adding Fe(II) of 30 mg·kg -1 as combined action of iron plaque and rhizosphere effect. Fluorescence microscope analysis showed that norfloxacin mainly distributed in the outside of root cell, which showed its translocation as apoplastic pathway in rice. Comparing with non-rhizosphere, more norfloxacin was accumulated in rhizosphere soil. Maybe, strong root oxidization (high Eh values) induced more iron oxide formation in rhizosphere and on root surface, which led to norfloxacin's mobility towards to rhizosphere through its strong adsorption of iron oxides and then promoted its uptake by rice on root surface.

Comparing root architectural models

NASA Astrophysics Data System (ADS)

Schnepf, Andrea; Javaux, Mathieu; Vanderborght, Jan

2017-04-01

Plant roots play an important role in several soil processes (Gregory 2006). Root architecture development determines the sites in soil where roots provide input of carbon and energy and take up water and solutes. However, root architecture is difficult to determine experimentally when grown in opaque soil. Thus, root architectural models have been widely used and been further developed into functional-structural models that are able to simulate the fate of water and solutes in the soil-root system (Dunbabin et al. 2013). Still, a systematic comparison of the different root architectural models is missing. In this work, we focus on discrete root architecture models where roots are described by connected line segments. These models differ (a) in their model concepts, such as the description of distance between branches based on a prescribed distance (inter-nodal distance) or based on a prescribed time interval. Furthermore, these models differ (b) in the implementation of the same concept, such as the time step size, the spatial discretization along the root axes or the way stochasticity of parameters such as root growth direction, growth rate, branch spacing, branching angles are treated. Based on the example of two such different root models, the root growth module of R-SWMS and RootBox, we show the impact of these differences on simulated root architecture and aggregated information computed from this detailed simulation results, taking into account the stochastic nature of those models. References Dunbabin, V.M., Postma, J.A., Schnepf, A., Pagès, L., Javaux, M., Wu, L., Leitner, D., Chen, Y.L., Rengel, Z., Diggle, A.J. Modelling root-soil interactions using three-dimensional models of root growth, architecture and function (2013) Plant and Soil, 372 (1-2), pp. 93 - 124. Gregory (2006) Roots, rhizosphere and soil: the route to a better understanding of soil science? European Journal of Soil Science 57: 2-12.

Expression of characteristics of ammonium nutrition as affected by pH of the root medium

NASA Technical Reports Server (NTRS)

Chaillou, S.; Vessey, J. K.; Morot-Gaudry, J. F.; Raper, C. D. Jr; Henry, L. T.; Boutin, J. P.

1991-01-01

To study the effect of root-zone pH on characteristic responses of NH4+ -fed plants, soybeans (Glycine max inverted question markL. inverted question mark Merr. cv. Ransom) were grown in flowing solution culture for 21 d on four sources of N (1.0 mol m-3 NO3-, 0.67 mol m-3 NO3- plus 0.33 mol m-3 NH4+, 0.33 mol m-3 NO3- plus 0.67 mol m-3 NH4+, and 1.0 mol m-3 NH4+) with nutrient solutions maintained at pH 6.0, 5.5, 5.0, and 4.5. Amino acid concentration increased in plants grown with NH4+ as the sole source of N at all pH levels. Total amino acid concentration in the roots of NH4+ -fed plants was 8 to 10 times higher than in NO3(-)-fed plants, with asparagine accounting for more than 70% of the total in the roots of these plants. The concentration of soluble carbohydrates in the leaves of NH4+ -fed plants was greater than that of NO3(-)-fed plants, but was lower in roots of NH4+ -fed plants, regardless of pH. Starch concentration was only slightly affected by N source or root-zone pH. At all levels of pH tested, organic acid concentration in leaves was much lower when NH4+ was the sole N source than when all or part of the N was supplied as NO3-. Plants grown with mixed NO3- plus NH4+ N sources were generally intermediate between NO3(-)- and NH4+ -fed plants. Thus, changes in tissue composition characteristic of NH4+ nutrition when root-zone pH was maintained at 4.5 and growth was reduced, still occurred when pH was maintained at 5.0 or above, where growth was not affected. The changes were slightly greater at pH 4.5 than at higher pH levels.

Comparative Analysis of Arabidopsis Ecotypes Reveals a Role for Brassinosteroids in Root Hydrotropism1[OPEN

PubMed Central

Wang, Meng; Yuan, Wei; Ren, Yan; Li, Ying; Zhang, Na; Kronzucker, Herbert J.

2018-01-01

Plant roots respond to soil moisture gradients and remodel their growth orientation toward water through hydrotropism, a process vital for acclimation to a changing soil environment. Mechanisms underlying the root hydrotropic response, however, remain poorly understood. Here, we examined hydrotropism in 31 Arabidopsis (Arabidopsis thaliana) ecotypes collected from different parts of the world and grown along moisture gradients in a specially designed soil-simulation system. Comparative transcriptome profiling and physiological analyses were carried out on three selected ecotypes, Wassilewskija (Ws), Columbia (Col-0) (strongly hydrotropic), Col-0 (moderately hydrotropic), and C24 (weakly hydrotropic), and in mutant lines with altered root hydrotropic responses. We show that H+ efflux, Ca2+ influx, redox homeostasis, epigenetic regulation, and phytohormone signaling may contribute to root hydrotropism. Among phytohormones, the role of brassinosteroids (BRs) was examined further. In the presence of an inhibitor of BR biosynthesis, the strong hydrotropic response observed in Ws was reduced. The root H+ efflux and primary root elongation also were inhibited when compared with C24, an ecotype that showed a weak hydrotropic response. The BR-insensitive mutant bri1-5 displayed higher rates of root growth inhibition and root curvature on moisture gradients in vertical or oblique orientation when compared with wild-type Ws. We also demonstrate that BRI1 (a BR receptor) interacts with AHA2 (a plasma membrane H+-ATPase) and that their expression patterns are highly coordinated. This synergistic action may contribute to the strong hydrotropism observed in Ws. Our results suggest that BR-associated H+ efflux is critical in the hydrotropic response of Arabidopsis roots. PMID:29439211

Control of cereal root pathogens with PGPR: The role of the natural antibiotic 2,4-diacetylphloroglucinol

USDA-ARS?s Scientific Manuscript database

Root pathogens are major impediments to grain production worldwide and must be controlled in order to significantly increase food production needed to feed >9 billion people by 2050. In the Pacific Northwest of the USA, wheat is grown under a wide range of climatic conditions. Two broad-spectrum ant...

Effects of Watering and Fertilization on Carbohydrate Reserves in Sugar Maple Seedlings

Treesearch

Clayton M., Jr. Carl; John R. Donnelly; Boyd W. Post

1978-01-01

Sugar maple seedlings, grown under three nutrient and three moisture levels, were analyzed after three growing seasons for starch and ethanol-soluble sugars. Analytical procedures are detailed in the appendix. Fertilization did not affect carbohydrate levels in stems or roots. Water stress caused a significant reduction in the amount of carbohydrates in stems and roots...

Aluminum fractions in root tips of slash pine and loblolly pine families differing in Al resistance

Treesearch

Jaroslaw Nowak; Alexander L. Friend

2005-01-01

Aluminum (Al) distribution among several cellular fractions was investigated in root tips of seedlings of one Al-resistant and one Al-sensitive family of slash pine (Pinus elliottii Engelm.) and loblolly pine (Pinus taeda L.) grown in nutrient solution containing 100 M AlCl3 (pH 4) for 167 h....

Chemistry and long-term decomposition of roots from Douglas-fir grown at elevated atmospheric CO2 and warming conditions

EPA Science Inventory

Elevated atmospheric CO2 and warming may affect litter quality of plants and its subsequent decomposition in forested ecosystems. Little data are available to test this potential feedback on root tissues. In this study, we used the fine (diameter ≤ 2 mm) and small (2-10 mm) roo...

Responses of growth and primary metabolism of water-stressed barley roots to rehydration

USDA-ARS?s Scientific Manuscript database

Barley seedlings [Hordeum vulgare L. Brant] were grown in pots in controlled environment chambers and drought treatments were imposed 11 days after sowing. Soil water content decreased from 92% to 10% after an additional 14 days of water stress. Shoot and root growth ceased after 4 and 9 days of wat...

Water deficit stress effects on corn (Zea mays, L.) root: shoot ratio

USDA-ARS?s Scientific Manuscript database

A study was conducted at Akron, CO, USA, on a Weld silt loam in 2004 to quantify the effects of water deficit stress on corn (Zea mays, L.) root and shoot biomass. Corn plants were grown under a range of soil bulk density and water conditions caused by previous tillage, crop rotation, and irrigation...

Arbuscule frequency in grapevine roots is more responsive to reduction in photosynthetic capacity than to increased levels of shoot phosphorus

USDA-ARS?s Scientific Manuscript database

We evaluated whether altering photosynthetic capacity or shoot P plays bigger role in regulating arbuscule abundance in fine roots of grapevine. Pinot noir grapevines were grown in an unsterilized vineyard soil and colonized by indigenous arbuscular mycorrhizal fungi (AMF) in two experiments where p...

Better Rooting Procedure to Enhance Survival Rate of Field Grown Malaysian Eksotika Papaya Transformed with 1-Aminocyclopropane-1-Carboxylic Acid Oxidase Gene

PubMed Central

Sekeli, Rogayah; Abdullah, Janna Ong; Namasivayam, Parameswari; Muda, Pauziah; Abu Bakar, Umi Kalsom

2013-01-01

A high survival rate for transformed papaya plants when transferred to the field is useful in the quest for improving the commercial quality traits. We report in this paper an improved rooting method for the production of transformed Malaysian Eksotika papaya with high survival rate when transferred to the field. Shoots were regenerated from embryogenic calli transformed with antisense and RNAi constructs of 1-aminocyclopropane-1-carboxylic acid oxidase (ACO) genes using the Agrobacterium tumefaciens-mediated transformation method. Regenerated transformed shoots, each measuring approximately 3-4 cm in height, were cultured in liquid half-strength Murashige and Skoog (MS) medium or sterile distilled water, and with either perlite or vermiculite supplementation. All the culturing processes were conducted either under sterile or nonsterile condition. The results showed that rooting under sterile condition was better. Shoots cultured in half-strength MS medium supplemented with vermiculite exhibited a 92.5% rooting efficiency while perlite showed 77.5%. The survival rate of the vermiculite-grown transformed papaya plantlets after transfer into soil, contained in polybags, was 94%, and the rate after transfer into the ground was 92%. Morpho-histological analyses revealed that the tap roots were more compact, which might have contributed to the high survival rates of the plantlets. PMID:25969786

Better rooting procedure to enhance survival rate of field grown malaysian eksotika papaya transformed with 1-aminocyclopropane-1-carboxylic Acid oxidase gene.

PubMed

Sekeli, Rogayah; Abdullah, Janna Ong; Namasivayam, Parameswari; Muda, Pauziah; Abu Bakar, Umi Kalsom

2013-01-01

A high survival rate for transformed papaya plants when transferred to the field is useful in the quest for improving the commercial quality traits. We report in this paper an improved rooting method for the production of transformed Malaysian Eksotika papaya with high survival rate when transferred to the field. Shoots were regenerated from embryogenic calli transformed with antisense and RNAi constructs of 1-aminocyclopropane-1-carboxylic acid oxidase (ACO) genes using the Agrobacterium tumefaciens-mediated transformation method. Regenerated transformed shoots, each measuring approximately 3-4 cm in height, were cultured in liquid half-strength Murashige and Skoog (MS) medium or sterile distilled water, and with either perlite or vermiculite supplementation. All the culturing processes were conducted either under sterile or nonsterile condition. The results showed that rooting under sterile condition was better. Shoots cultured in half-strength MS medium supplemented with vermiculite exhibited a 92.5% rooting efficiency while perlite showed 77.5%. The survival rate of the vermiculite-grown transformed papaya plantlets after transfer into soil, contained in polybags, was 94%, and the rate after transfer into the ground was 92%. Morpho-histological analyses revealed that the tap roots were more compact, which might have contributed to the high survival rates of the plantlets.

Root iron uptake efficiency of Ulmus laevis and U. minor and their distribution in soils of the Iberian Peninsula

PubMed Central

Venturas, Martin; Fernández, Victoria; Nadal, Paloma; Guzmán, Paula; Lucena, Juan J.; Gil, Luis

2014-01-01

The calcifuge and calcicole character of wild plants has been related to nutrient availability shortages, including iron (Fe)-deficiency. Surprisingly, just a few studies examined the relation between root Fe uptake and plant distribution in different soil types. We assessed the root Fe acquisition efficiency of two Ulmus species with calcareous (Ulmus minor) and siliceous (U. laevis) soil distribution patterns in the Iberian Peninsula. Seedlings of both elm species were grown hydroponically with different Fe concentrations during 6 weeks. Plant physiological responses to Fe-limiting conditions were evaluated as were the ferric reductase activity and proton (H+) extrusion capacity of the roots. Iron deprived elm seedlings of both species were stunted and suffered severe Fe-chlorosis symptoms. After Fe re-supply leaf chlorophyll concentrations rose according to species-dependent patterns. While U. minor leaves and seedlings re-greened evenly, U. laevis did so along the nerves of new growing leaves. U. minor had a higher root ferric reductase activity and H+-extrusion capability than U. laevis and maintained a better nutrient balance when grown under Fe-limiting conditions. The two elm species were found to have different Fe acquisition efficiencies which may be related to their natural distribution in calcareous and siliceous soils of the Iberian Peninsula. PMID:24723927

Polynuclear aromatic hydrocarbon uptake by carrots grown in sludge-amended soil

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wild, S.R.; Jones, K.C.

The uptake of polynuclear aromatic hydrocarbons (PAHs) from sewage sludge-amended soils by carrots (Daucus carota) was investigated. Carrots were grown in control soils and soils amended with three sludge application rates, 15, 55, and 180 t/ha. Applied sludge contained 17.2 mg [summation]PAH/kg, a concentration typical for a sludge derived from a rural area. Carrot foliage, root peels and root cores were analyzed for 15 PAH compounds. Carrots foliage PAH concentrations were unaffected by sludge applications (PAH loadings), but root peel PAH concentrations increased to a plateau concentration with increasing soil PAH levels. Low molecular weight PAH compounds dominate dindividual componentsmore » of the [summation]PAH load in the root tissues. The PAH concentrations detected in the root peels were all significantly lower than in the foliage, which receives PAH inputs from the atmosphere. Carrot core [summation]PAH concentrations were unaffected by sludge application, implying little or no transfer of PAHs from the peels to the core. About 70% of the PAH burden found in carrots was associated with the peels. Fresh weight carrot core concentrations were all <4.2 [mu]g/kg. Overall, this investigation suggests that the risks posed to human health by PAHs applied in sewage sludge to arable soils are minimal.« less

Root Zone Cooling and Exogenous Spermidine Root-Pretreatment Promoting Lactuca sativa L. Growth and Photosynthesis in the High-temperature Season

PubMed Central

Sun, Jin; Lu, Na; Xu, Hongjia; Maruo, Toru; Guo, Shirong

2016-01-01

Root zone high-temperature stress is a major factor limiting hydroponic plant growth during the high-temperature season. The effects of root zone cooling (RZC; at 25°C) and exogenous spermidine (Spd) root-pretreatment (SRP, 0.1 mM) on growth, leaf photosynthetic traits, and chlorophyll fluorescence characteristics of hydroponic Lactuca sativa L. grown in a high-temperature season (average temperature > 30°C) were examined. Both treatments significantly promoted plant growth and photosynthesis in the high-temperature season, but the mechanisms of photosynthesis improvement in the hydroponic grown lettuce plants were different between the RZC and SRP treatments. The former improved plant photosynthesis by increasing stoma conductance (Gs) to enhance CO2 supply, thus promoting photosynthetic electron transport activity and phosphorylation, which improved the level of the photochemical efficiency of photosystem II (PSII), rather than enhancing CO2 assimilation efficiency. The latter improved plant photosynthesis by enhancing CO2 assimilation efficiency, rather than stomatal regulation. Combination of RZC and SRP significantly improved PN of lettuce plants in a high-temperature season by both improvement of Gs to enhance CO2 supply and enhancement of CO2 assimilation. The enhancement of photosynthetic efficiency in both treatments was independent of altering light-harvesting or excessive energy dissipation. PMID:27047532

Differential growth responses of Brachypodium distachyon genotypes to inoculation with plant growth promoting rhizobacteria.

PubMed

do Amaral, Fernanda P; Pankievicz, Vânia C S; Arisi, Ana Carolina M; de Souza, Emanuel M; Pedrosa, Fabio; Stacey, Gary

2016-04-01

Plant growth promoting rhizobacteria (PGPR) can associate and enhance the growth of important crop grasses. However, in most cases, the molecular mechanisms responsible for growth promotion are not known. Such research could benefit by the adoption of a grass model species that showed a positive response to bacterial inoculation and was amenable to genetic and molecular research methods. In this work we inoculated different genotypes of the model grass Brachypodium distachyon with two, well-characterized PGPR bacteria, Azospirillum brasilense and Herbaspirillum seropedicae, and evaluated the growth response. Plants were grown in soil under no nitrogen or with low nitrogen (i.e., 0.5 mM KNO3). A variety of growth parameters (e.g., shoot height, root length, number of lateral roots, fresh and dry weight) were measured 35 days after inoculation. The data indicate that plant genotype plays a very important role in determining the plant response to PGPR inoculation. A positive growth response was observed with only four genotypes grown under no nitrogen and three genotypes tested under low nitrogen. However, in contrast, relatively good root colonization was seen with most genotypes, as measured by drop plate counting and direct, microscopic examination of roots. In particular, the endophytic bacteria H. seropedicae showed strong epiphytic and endophytic colonization of roots.

Spaceflight exposure effects on transcription, activity, and localization of alcohol dehydrogenase in the roots of Arabidopsis thaliana.

PubMed Central

Porterfield, D M; Matthews, S W; Daugherty, C J; Musgrave, M E

1997-01-01

Although considerable research and speculation have been directed toward understanding a plant's perception of gravity and the resulting gravitropic responses, little is known about the role of gravity-dependent physical processes in normal physiological function. These studies were conducted to determine whether the roots of plants exposed to spaceflight conditions may be experiencing hypoxia. Arabidopsis thaliana (L.) Heynh. plants were grown in agar medium during 6 or 11 d of spaceflight exposure on shuttle missions STS-54 (CHROMEX-03) and STS-68 (CHROMEX-05), respectively. The analysis included measurement of agar redox potential and root alcohol dehydrogenase (ADH) activity, localization, and expression. ADH activity increased by 89% as a result of spaceflight exposure for both CHROMEX-03 and -05 experiments, and ADH RNase protection assays revealed a 136% increase in ADH mRNA. The increase in ADH activity associated with the spaceflight roots was realized by a 28% decrease in oxygen availability in a ground-based study; however, no reduction in redox potential was observed in measurements of the spaceflight bulk agar. Spaceflight exposure appears to effect a hypoxic response in the roots of agar-grown plants that may be caused by changes in gravity-mediated fluid and/or gas behavior. PMID:9085569

Root Zone Cooling and Exogenous Spermidine Root-Pretreatment Promoting Lactuca sativa L. Growth and Photosynthesis in the High-temperature Season.

PubMed

Sun, Jin; Lu, Na; Xu, Hongjia; Maruo, Toru; Guo, Shirong

2016-01-01

Root zone high-temperature stress is a major factor limiting hydroponic plant growth during the high-temperature season. The effects of root zone cooling (RZC; at 25°C) and exogenous spermidine (Spd) root-pretreatment (SRP, 0.1 mM) on growth, leaf photosynthetic traits, and chlorophyll fluorescence characteristics of hydroponic Lactuca sativa L. grown in a high-temperature season (average temperature > 30°C) were examined. Both treatments significantly promoted plant growth and photosynthesis in the high-temperature season, but the mechanisms of photosynthesis improvement in the hydroponic grown lettuce plants were different between the RZC and SRP treatments. The former improved plant photosynthesis by increasing stoma conductance (G s) to enhance CO2 supply, thus promoting photosynthetic electron transport activity and phosphorylation, which improved the level of the photochemical efficiency of photosystem II (PSII), rather than enhancing CO2 assimilation efficiency. The latter improved plant photosynthesis by enhancing CO2 assimilation efficiency, rather than stomatal regulation. Combination of RZC and SRP significantly improved P N of lettuce plants in a high-temperature season by both improvement of G s to enhance CO2 supply and enhancement of CO2 assimilation. The enhancement of photosynthetic efficiency in both treatments was independent of altering light-harvesting or excessive energy dissipation.

Spaceflight exposure effects on transcription, activity, and localization of alcohol dehydrogenase in the roots of Arabidopsis thaliana

NASA Technical Reports Server (NTRS)

Porterfield, D. M.; Matthews, S. W.; Daugherty, C. J.; Musgrave, M. E.

1997-01-01

Although considerable research and speculation have been directed toward understanding a plant's perception of gravity and the resulting gravitropic responses, little is known about the role of gravity-dependent physical processes in normal physiological function. These studies were conducted to determine whether the roots of plants exposed to spaceflight conditions may be experiencing hypoxia. Arabidopsis thaliana (L.) Heynh. plants were grown in agar medium during 6 or 11 d of spaceflight exposure on shuttle missions STS-54 (CHROMEX-03) and STS-68 (CHROMEX-05), respectively. The analysis included measurement of agar redox potential and root alcohol dehydrogenase (ADH) activity, localization, and expression. ADH activity increased by 89% as a result of spaceflight exposure for both CHROMEX-03 and -05 experiments, and ADH RNase protection assays revealed a 136% increase in ADH mRNA. The increase in ADH activity associated with the spaceflight roots was realized by a 28% decrease in oxygen availability in a ground-based study; however, no reduction in redox potential was observed in measurements of the spaceflight bulk agar. Spaceflight exposure appears to effect a hypoxic response in the roots of agar-grown plants that may be caused by changes in gravity-mediated fluid and/or gas behavior.

Access to mycorrhizal networks and roots of trees: importance for seedling survival and resource transfer.

PubMed

Teste, François P; Simard, Suzanne W; Durall, Daniel M; Guy, Robert D; Jones, Melanie D; Schoonmaker, Amanda L

2009-10-01

Mycorrhizal networks (MNs) are fungal hyphae that connect roots of at least two plants. It has been suggested that these networks are ecologically relevant because they may facilitate interplant resource transfer and improve regeneration dynamics. This study investigated the effects of MNs on seedling survival, growth and physiological responses, interplant resource (carbon and nitrogen) transfer, and ectomycorrhizal (EM) fungal colonization of seedlings by trees in dry interior Douglas-fir (Pseudotsuga menziesii var. glauca) forests. On a large, recently harvested site that retained some older trees, we established 160 isolated plots containing pairs of older Douglas-fir "donor" trees and either manually sown seed or planted Douglas-fir "receiver" seedlings. Seed- and greenhouse-grown seedlings were sown and planted into four mesh treatments that served to restrict MN access (i.e., planted into mesh bags with 0.5-, 35-, 250-microm pores, or without mesh). Older trees were pulse labeled with carbon (13CO2) and nitrogen (15NH4(15)NO3) to quantify resource transfer. After two years, seedlings grown from seed in the field had the greatest survival and received the greatest amounts of transferred carbon (0.0063% of donor photo-assimilates) and nitrogen (0.0018%) where they were grown without mesh; however, planted seedlings were not affected by access to tree roots and hyphae. Size of "donor" trees was inversely related to the amount of carbon transferred to seedlings. The potential for MNs to form was high (based on high similarity of EM communities between hosts), and MN-mediated colonization appeared only to be important for seedlings grown from seed in the field. These results demonstrate that MNs and mycorrhizal roots of trees may be ecologically important for natural regeneration in dry forests, but it is still uncertain whether resource transfer is an important mechanism underlying seedling establishment.

Regulation of root morphogenesis in arbuscular mycorrhizae: what role do fungal exudates, phosphate, sugars and hormones play in lateral root formation?

PubMed Central

Fusconi, Anna

2014-01-01

Background Arbuscular mycorrhizae (AMs) form a widespread root–fungus symbiosis that improves plant phosphate (Pi) acquisition and modifies the physiology and development of host plants. Increased branching is recognized as a general feature of AM roots, and has been interpreted as a means of increasing suitable sites for colonization. Fungal exudates, which are involved in the dialogue between AM fungi and their host during the pre-colonization phase, play a well-documented role in lateral root (LR) formation. In addition, the increased Pi content of AM plants, in relation to Pi-starved controls, as well as changes in the delivery of carbohydrates to the roots and modulation of phytohormone concentration, transport and sensitivity, are probably involved in increasing root system branching. Scope This review discusses the possible causes of increased branching in AM plants. The differential root responses to Pi, sugars and hormones of potential AM host species are also highlighted and discussed in comparison with those of the non-host Arabidopsis thaliana. Conclusions Fungal exudates are probably the main compounds regulating AM root morphogenesis during the first colonization steps, while a complex network of interactions governs root development in established AMs. Colonization and high Pi act synergistically to increase root branching, and sugar transport towards the arbusculated cells may contribute to LR formation. In addition, AM colonization and high Pi generally increase auxin and cytokinin and decrease ethylene and strigolactone levels. With the exception of cytokinins, which seem to regulate mainly the root:shoot biomass ratio, these hormones play a leading role in governing root morphogenesis, with strigolactones and ethylene blocking LR formation in the non-colonized, Pi-starved plants, and auxin inducing them in colonized plants, or in plants grown under high Pi conditions. PMID:24227446

Soybean cultivation for Bioregenerative Life Support Systems (BLSSs): The effect of hydroponic system and nitrogen source

NASA Astrophysics Data System (ADS)

Paradiso, Roberta; Buonomo, Roberta; Dixon, Mike A.; Barbieri, Giancarlo; De Pascale, Stefania

2014-02-01

Soybean [Glycine max (L.) Merr.] is one of the plant species selected within the European Space Agency (ESA) Micro-Ecological Life Support System Alternative (MELiSSA) project for hydroponic cultivation in Biological Life Support Systems (BLSSs), because of the high nutritional value of seeds. Root symbiosis of soybean with Bradirhizobium japonicum contributes to plant nutrition in soil, providing ammonium through the bacterial fixation of atmospheric nitrogen. The aim of this study was to evaluate the effects of two hydroponic systems, Nutrient Film Technique (NFT) and cultivation on rockwool, and two nitrogen sources in the nutrient solution, nitrate (as Ca(NO3)2 and KNO3) and urea (CO(NH2)2), on root symbiosis, plant growth and seeds production of soybean. Plants of cultivar 'OT8914', inoculated with B. japonicum strain BUS-2, were grown in a growth chamber, under controlled environmental conditions. Cultivation on rockwool positively influenced root nodulation and plant growth and yield, without affecting the proximate composition of seeds, compared to NFT. Urea as the sole source of N drastically reduced the seed production and the harvest index of soybean plants, presumably because of ammonium toxicity, even though it enhanced root nodulation and increased the N content of seeds. In the view of large-scale cultivation for space colony on planetary surfaces, the possibility to use porous media, prepared using in situ resources, should be investigated. Urea can be included in the nutrient formulation for soybean in order to promote bacterial activity, however a proper ammonium/nitrate ratio should be maintained.

Explanation of pole blight from responses of seedlings grown in modified environments

Treesearch

Charles D. Leaphart; Ed F. Wicker

1966-01-01

Seedlings of Douglas fir, grand fir, western larch, western red cedar, and western white pine were grown in modified environments for four growing seasons to see whether characteristic growth responses of roots and shoots might suggest a cause for pole blight of white pine. Environments included three soil profiles (topsoil, hardpan, and rock) and two moisture regimes...

Root growth dynamics linked to above-ground growth in walnut (Juglans regia).

PubMed

Contador, Maria Loreto; Comas, Louise H; Metcalf, Samuel G; Stewart, William L; Porris Gomez, Ignacio; Negron, Claudia; Lampinen, Bruce D

2015-07-01

Examination of plant growth below ground is relatively scant compared with that above ground, and is needed to understand whole-plant responses to the environment. This study examines whether the seasonal timing of fine root growth and the spatial distribution of this growth through the soil profile varies in response to canopy manipulation and soil temperature. Plasticity in the seasonal timing and vertical distribution of root production in response to canopy and soil water manipulation was analysed in field-grown walnut (Juglans regia 'Chandler') using minirhizotron techniques. Root production in walnuts followed a unimodal curve, with one marked flush of root growth starting in mid-May, with a peak in mid-June. Root production declined later in the season, corresponding to increased soil temperature, as well as to the period of major carbohydrate allocation to reproduction. Canopy and soil moisture manipulation did not influence the timing of root production, but did influence the vertical distribution of roots through the soil profile. Water deficit appeared to promote root production in deeper soil layers for mining soil water. Canopy removal appeared to promote shallow root production. The findings of this study add to growing evidence that root growth in many ecosystems follows a unimodal curve with one marked flush of root growth in coordination with the initial leaf flush of the season. Root vertical distribution appeared to have greater plasticity than timing of root production in this system, with temperature and/or carbohydrate competition constraining the timing of root growth. Effects on root distribution can have serious impacts on trees, with shallow rooting having negative impacts in years with limited soil water or positive impacts in years with wet springs, and deep rooting having positive impacts on soil water mining from deeper soil layers but negative impacts in years with wet springs. © The Author 2015. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Arbuscular mycorrhiza improve growth, nitrogen uptake, and nitrogen use efficiency in wheat grown under elevated CO2.

PubMed

Zhu, Xiancan; Song, Fengbin; Liu, Shengqun; Liu, Fulai

2016-02-01

Effects of the arbuscular mycorrhizal (AM) fungus Rhizophagus irregularis on plant growth, carbon (C) and nitrogen (N) accumulation, and partitioning was investigated in Triticum aestivum L. plants grown under elevated CO2 in a pot experiment. Wheat plants inoculated or not inoculated with the AM fungus were grown in two glasshouse cells with different CO2 concentrations (400 and 700 ppm) for 10 weeks. A (15)N isotope labeling technique was used to trace plant N uptake. Results showed that elevated CO2 increased AM fungal colonization. Under CO2 elevation, AM plants had higher C concentration and higher plant biomass than the non-AM plants. CO2 elevation did not affect C and N partitioning in plant organs, while AM symbiosis increased C and N allocation into the roots. In addition, plant C and N accumulation, (15)N recovery rate, and N use efficiency (NUE) were significantly higher in AM plants than in non-AM controls under CO2 enrichment. It is concluded that AM symbiosis favors C and N partitioning in roots, increases C accumulation and N uptake, and leads to greater NUE in wheat plants grown at elevated CO2.

Use of ex vitro composite plants to study the interaction of cowpea (Vigna unguiculata L.) with the root parasitic angiosperm Striga gesnerioides

PubMed Central

2012-01-01

Background Cowpea (Vigna unguiculata L.) is an important grain and forage legume grown throughout sub-Saharan Africa primarily by subsistence farmers on poor, drought prone soils. Genetic improvement of the crop is being actively pursued and numerous functional genomics studies are underway aimed at characterizing gene controlling key agronomic characteristics for disease and pest resistances. Unfortunately, similar to other legumes, efficient plant transformation technology is a rate-limiting step in analysis of gene function in cowpea. Results Here we describe an optimized protocol for the rapid generation of transformed hairy roots on ex vitro composite plants of cowpea using Agrobacterium rhizogenes. We further demonstrate the applicability of cowpea composite plants to study gene expression involved in the resistance response of the plant roots to attack by the root parasitic weed, Striga gesnerioides. The utility of the new system and critical parameters of the method are described and discussed herein. Conclusions Cowpea composite plants offer a rapid alternative to methods requiring stable transformation and whole plant regeneration for studying gene expression in resistance or susceptibility responses to parasitic weeds. Their use can likely be readily adapted to look at the effects of both ectopic gene overexpression as well as gene knockdown of root associated defense responses and to the study of a broader range of root associated physiological and aphysiological processes including root growth and differentiation as well as interactions with other root pests, parasites, and symbionts. PMID:22741546

Thermotropism by primary roots of maize

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fortin, M.-C.; Poff, K.L.

1990-05-01

Sensing in the roots of higher plants has long been recognized to be restricted mainly to gravitropism and thigmotropism. However, root responses to temperature gradients have not been extensively studied. We have designed experiments under controlled conditions to test if and how root direction of maize can be altered by thermal gradients perpendicular to the gravity vector. Primary roots of maize grown on agar plates exhibit positive thermotropism (curvature toward the warmer temperature) when exposed to gradients of 0.5 to 4.2{degree}C cm{sup {minus}1}. The extent of thermotropism depends on the temperature gradient and the temperature at which the root ismore » placed within the gradient. The curvature cannot be accounted for by differential growth as a direct effect of temperature on each side of the root.« less

Inhibition of root elongation in microgravity by an applied electric field

NASA Technical Reports Server (NTRS)

Wolverton, C.; Mullen, J. L.; Aizawa, S.; Yoshizaki, I.; Kamigaichi, S.; Mukai, C.; Shimazu, T.; Fukui, K.; Evans, M. L.; Ishikawa, H.

1999-01-01

Roots grown in an applied electric field demonstrate a bidirectional curvature. To further understand the nature of this response and its implications for the regulation of differential growth, we applied an electric field to roots growing in microgravity. We found that growth rates of roots in microgravity were higher than growth rates of ground controls. Immediately upon application of the electric field, root elongation was inhibited. We interpret this result as an indication that, in the absence of a gravity stimulus, the sensitivity of the root to an applied electric stimulus is increased. Further space experiments are required to determine the extent to which this sensitivity is shifted. The implications of this result are discussed in relation to gravitropic signaling and the regulation of differential cell elongation in the root.

Non-invasive analysis of root-soil interaction using three complementary imaging approaches

NASA Astrophysics Data System (ADS)

Haber-Pohlmeier, Sabina; Tötzke, Christian; Pohlmeier, Andreas; Rudolph-Mohr, Nicole; Kardjilov, Nikolay; Lehmann, Eberhard; Oswald, Sascha E.

2016-04-01

Plant roots are known to modify physical, chemical and biological properties of the rhizosphere, thereby, altering conditions for water and nutrient uptake. We aim for capturing the dynamic processes occurring at the soil-root interface in situ. A combination of neutron (NI), magnetic resonance (MRI) and micro-focus X-ray tomography (CT) is applied to monitor the rhizosphere of young plants grown in sandy soil in cylindrical containers (diameter 3 cm). A novel transportable low field MRI system is operated directly at the neutron facility allowing for combined measurements of the very same sample capturing the same hydro-physiological state. The combination of NI, MRI and CT provides three-dimensional access to the root system in respect to structure and hydraulics of the rhizosphere and the transport of dissolved marker substances. The high spatial resolution of neutron imaging and its sensitivity for water can be exploited for the 3D analysis of the root morphology and detailed mapping of three-dimensional water content at the root soil interface and the surrounding soil. MRI has the potential to yield complementary information about the mobility of water, which can be bound in small pores or in the polymeric network of root exudates (mucilage layer). We inject combined tracers (GdDPTA or D2O) to study water fluxes through soil, rhizosphere and roots. Additional CT measurements reveal mechanical impacts of roots on the local microstructure of soil, e.g. showing soil compaction or the formation of cracks. We co-register the NT, MRI and CT data to integrate the complementary information into an aligned 3D data set. This allows, e.g., for co-localization of compacted soil regions or cracks with the specific local soil hydraulics, which is needed to distinguish the contribution of root exudation from mechanical impacts when interpreting altered hydraulic properties of the rhizosphere. Differences between rhizosphere and bulk soil can be detected and interpreted in terms of root growth, root exudation, and root water uptake. Thus, we demonstrate that such a multi-imaging approach can be used as powerful tool contributing to a more comprehensive picture of the rhizosphere.

Mapping the metal uptake in plants from Jasper Ridge Biological Preserve using synchrotron micro-focused X-ray fluorescence spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lo, Allison

2015-08-20

Serpentine soil originates in the Earth’s mantle and contains high concentrations of potentially toxic transition metals. Although serpentine soil limits plant growth, endemic and adapted plants at Jasper Ridge Biological Preserve, located behind SLAC National Accelerator Laboratory, can tolerate these conditions. Serpentine soil and seeds belonging to native California and invasive plants were collected at Jasper Ridge. The seeds were grown hydroponically and on serpentine and potting soil to examine the uptake and distribution of ions in the roots and shoots using synchrotron micro-focused X-ray fluorescence spectroscopy. The results were used to determine differences between serpentine-tolerant plants. Rye grown onmore » potting soil was enriched in Ni, Fe, Mn, and Cr compared to purple needlegrass grown on serpentine soil. Serpentine vegetation equally suppressed the uptake of Mn, Ni, and Fe in the roots and shoots. The uptake of Ca and Mg affected the uptake of other elements such as K, S, and P.« less

Mapping the Metal Uptake in Plants from Jasper Ridge Biological Preserve - Oral Presentation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lo, Allison

2015-08-24

Serpentine soil originates in the Earth’s mantle and contains high concentrations of potentially toxic transition metals. Although serpentine soil limits plant growth, endemic and adapted plants at Jasper Ridge Biological Preserve, located behind SLAC National Accelerator Laboratory, can tolerate these conditions. Serpentine soil and seeds belonging to native California and invasive plants were collected at Jasper Ridge. The seeds were grown hydroponically and on serpentine and potting soil to examine the uptake and distribution of ions in the roots and shoots using synchrotron micro-focused X-ray fluorescence spectroscopy. The results were used to determine differences between serpentinetolerant plants. Rye grown onmore » potting soil was enriched in Ni, Fe, Mn, and Cr compared to purple needlegrass grown on serpentine soil. Serpentine vegetation equally suppressed the uptake of Mn, Ni, and Fe in the roots and shoots. The uptake of Ca and Mg affected the uptake of other elements such as K, S, and P.« less

Impacts of root traits and genotypic diversity in switchgrass cropping systems on biogeochemical cycling of soil carbon and nitrogen

NASA Astrophysics Data System (ADS)

De Graaff, M. A.; Jastrow, J. D.; Adkins, J.; Johns, A. C.; Morris, G.; Six, J.

2016-12-01

Land-use change for bioenergy production can create greenhouse gas (GHG) emissions through disturbance of soil carbon (C) pools, but native species with extensive root systems may rapidly repay the GHG debt by enhancing soil C sequestration upon land-use change, particularly when grown in diverse mixtures. Here we investigated how root traits and genotypic diversity in switchgrass (Panicum virgatum) impacts yield, nitrogen (N) cycling and soil C stabilization. Owing to extensive within-species variation in root morphology and architecture among the switchgrass cultivars, we hypothesized that increasing cultivar diversity would enhance belowground niche differentiation, thereby increasing N use efficiency, yield, and ultimately soil C stabilization. Our experiment was conducted at the Fermilab National Environmental Research Park, in northeastern Illinois, USA, where we varied the level of switchgrass genotypic diversity using various local and non-local cultivars (1, 2, 4, or 6 cultivars per plot) in a replicated field trial. We found that genotypic mixtures had one-third higher biomass production than the average monoculture, and no monoculture was significantly higher yielding than the average mixture. Further, year-to-year variation in yields was reduced in the mixture of switchgrass relative to the species monocultures. Despite positive impacts of increased intraspecific diversity on biomass production, we found no effect on N use efficiency, or soil C sequestration. However there were differences among cultivars in soil C input and soil C stabilization. These differences were related to specific root length (SRL), where greater SRL was accompanied by more root-derived soil C. Our findings suggest SRL is a root trait that affects soil C input, and that genotypic mixtures could help provide high, stable yields of high-quality biomass feedstocks.

Comparison of the Antimicrobial Efficacy of the EndoVac System and Conventional Needle Irrigation in Primary Molar Root Canals.

PubMed

Buldur, Burak; Kapdan, Arife

The purpose of this study was to compare the antimicrobial efficacy of the EndoVac system and conventional needle irrigation to eliminate E faecalis in primary molar root canals. 60 extracted human primary second molar roots were instrumented up to an apical size .04/35 and randomly divided into two groups; Group 1: conventional needle (n=30) and Group 2: EndoVac (n=30), and four subgroups (two experimental subgroups; (a) 2.5% sodium hypochlorite (NaOCl) + ethylenediaminetetraacetic acid (EDTA) (n=20), (b) ozonated water (OW) + EDTA (n=20), and control groups (c) 5.25% NaOCl (n=10) and (d) saline (n=10). All roots were sterilized and then inoculated with E.faecalis. Before and after final irrigation procedures, root canals were sampled and the grown colony forming units (CFUs) were counted. Data were analyzed by Kruskall-Wallis and Mann-Whitney U tests using a 0.05 significance level. The EndoVac reduced more bacteria than the conventional needle did but it was not statistically significant (p>0.05). NaOCl alone or followed by EDTA totally eliminated bacteria. OW + EDTA showed higher reduction of bacteria but could not totally eliminate bacterias. In the context of bacterial elimination, the EndoVac was not significantly better than the conventional needle. Although, there were fewer CFU/mg when using EndoVac, there was not any statistically significant superiority to conventional needle irrigation. An OW+EDTA regimen showed antibacterial effect in the primary molar root canals but it was significantly less effective than NaOCl+EDTA.

A recirculating hydroponic system for studying peanut (Arachis hypogaea L.)

NASA Technical Reports Server (NTRS)

Mackowiak, C. L.; Wheeler, R. M.; Stutte, G. W.; Yorio, N. C.; Ruffe, L. M.; Sager, J. C. (Principal Investigator)

1998-01-01

Peanut (Arachis hypogaea L.) plants were grown hydroponically, using continuously recirculating nutrient solution. Two culture tray designs were tested; one tray design used only nutrient solution, while the other used a sphagnum-filled pod development compartment just beneath the cover and above the nutrient solution. Both trays were fitted with slotted covers to allow developing gynophores to reach the root zone. Peanut seed yields averaged 350 gm-2 dry mass, regardless of tray design, suggesting that substrate is not required for hydroponic peanut production.

Distribution of root exudates and mucilage in the rhizosphere: combining 14C imaging with neutron radiography

NASA Astrophysics Data System (ADS)

Holz, Maire; Carminati, Andrea; Kuzyakov, Yakov

2015-04-01

Water and nutrients will be the major factors limiting food production in future. Plant roots employ various mechanisms to increase the access to limited soil resources. Low molecular weight organic substances released by roots into the rhizosphere increase nutrient availability by interactions with microorganisms, while mucilage improves water availability under low moisture conditions. Though composition and quality of these substances have intensively been investigated, studies on the spatial distribution and quantification of exudates in soil are scarce. Our aim was to quantify and visualize root exudates and mucilage distribution around growing roots using neutron radiography and 14C imaging depending on drought stress. Plants were grown in rhizotrons well suited for neutron radiography and 14C imaging. Plants were exposed to various soil water contents experiencing different levels of drought stress. The water content in the rhizosphere was imaged during several drying/wetting cycles by neutron radiography. The radiographs taken a few hours after irrigation showed a wet region around the root tips showing the allocation and distribution of mucilage. The increased water content in the rhizosphere of the young root segments was related to mucilage concentrations by parameterization described in Kroener et al. (2014). In parallel 14C imaging of root after 14CO2 labeling of shoots (Pausch and Kuzyakov 2011) showed distribution of rhizodeposits including mucilage. Three days after setting the water content, plants were labeled in 14CO2 atmosphere. Two days later 14C distribution in soil was imaged by placing a phosphor-imaging plate on the rhizobox. To quantify rhizodeposition, 14C activity on the image was related to the absolute 14C activity in the soil and root after destructive sampling. By comparing the amounts of mucilage (neutron radiography) with the amount of total root derived C (14C imaging), we were able to differentiate between mucilage and root exudates. We found that mucilage and 14C concentrations were higher around the young root segments. Mucilage concentration was particularly high in the most apical 3-5 cm of the roots. Drought stress increased 14C exudation relative to C fixation and led to higher mucilage concentrations around roots. However, it remains unclear, whether the lower mucilage concentration around roots grown at higher soil moisture was caused by the faster diffusion of mucilage in wet soils. Therefore, a second experiment was focused on diffusion of mucilage in soil at varying water contents. The diffusion of mucilage in soil was not very sensitive to soil water content. We conclude that mucilage release was higher for plants exposed to drought stress. In summary, the combination of neutron radiography and 14C imaging can successfully be used to visualize and to quantify the distribution of mucilage and root exudates in the rhizosphere of plants grown in soil. References Kroener, E., Zarebanadkouki, M., Kaestner, A., & Carmintati, A. (2014). Nonequilibrium water dynamics in the rhizosphere: How mucilage affects water flow in soils. Water Resources Research, 37. Pausch, J., & Kuzyakov, Y. (2011). Photoassimilate allocation and dynamics of hotspots in roots visualized by 14C phosphor imaging. Journal of Plant Nutrition and Soil Science, 174(1), 12-19.

Nutrient management effects on sweetpotato genotypes under controlled environment

NASA Technical Reports Server (NTRS)

David, P. P.; Bonsi, C. K.; Trotman, A. A.; Douglas, D. Z.

1996-01-01

Sweetpotato is one of several crops recommended by National Aeronautics and Space Administration (NASA) for bioregenerative life support studies. One of the objectives of the Tuskegee University NASA Center is to optimize growth conditions for adaptability of sweetpotatoes for closed bioregenerative systems. The role of nutrient solution management as it impacts yield has been one of the major thrusts in these studies. Nutrient solution management protocol currently used consists of a modified half Hoagland solution that is changed at 14-day intervals. Reservoirs are refilled with deionized water if the volume of the nutrient solution was reduced to 8 liters or less before the time of solution change. There is the need to recycle and replenish nutrient solution during crop growth, rather than discard at 14 day intervals as previously done, in order to reduce waste. Experiments were conducted in an environmental growth room to examine the effects of container size on the growth of several sweetpotato genotypes grown under a nutrient replenishment protocol. Plants were grown from vine cuttings of 15cm length and were planted in 0.15 x 0.15 x 1.2m growth channels using a closed nutrient film technique system. Nutrient was supplied in a modified half strength Hoagland's solution with a 1:2.4 N:K ratio. Nutrient replenishment protocol consisted of daily water replenishment to a constant volume of 30.4 liters in the small containers and 273.6 liters in the large container. Nutrients were replenished as needed when the EC of the nutrient solution fell below 1200 mhos/cm. The experimental design used was a split-plot with the main plot being container size and genotypes as the subplot. Nine sweetpotato genotypes were evaluated. Results showed no effect of nutrient solution container size on storage root yield, foliage fresh and dry mass, leaf area or vine length. However, plants grown using the large nutrient solution container accumulated more storage root dry mass than those with the small containers. Although plants grown with the smaller containers showed greater water uptake, plant nutrient uptake was lower than with the larger container. All genotypes evaluated showed variation in their responses to all parameters measured.

Liquid in vitro culture for the propagation of Arundo donax.

PubMed

Herrera-Alamillo, Miguel Angel; Robert, Manuel L

2012-01-01

We describe a simple and inexpensive plant micropropagation system for giant reed (Arundo donax L.) that uses axillary buds from the lateral stems of elite plants selected from field- or nursery-grown plants. The buds, attached to the stems are cultured in stationary liquid MS culture medium, supplemented with indole 3-acetic acid and kinetin. This formulation is the only one required for all the stages. Contrary to what happens in semisolid medium where roots are not formed, the plants cultured in liquid medium are whole plants with shoots and roots that develop at the same time. The survival rate of these plants when transferred to soil is close to 100% during acclimatization. A clonal line of 900 plants from a single mother plant can be produced in 4 months.

Arabidopsis Root-Type Ferredoxin:NADP(H) Oxidoreductase 2 is Involved in Detoxification of Nitrite in Roots.

PubMed

Hachiya, Takushi; Ueda, Nanae; Kitagawa, Munenori; Hanke, Guy; Suzuki, Akira; Hase, Toshiharu; Sakakibara, Hitoshi

2016-11-01

Ferredoxin:NADP(H) oxidoreductase (FNR) plays a key role in redox metabolism in plastids. Whereas leaf FNR (LFNR) is required for photosynthesis, root FNR (RFNR) is believed to provide electrons to ferredoxin (Fd)-dependent enzymes, including nitrite reductase (NiR) and Fd-glutamine-oxoglutarate aminotransferase (Fd-GOGAT) in non-photosynthetic conditions. In some herbal species, however, most nitrate reductase activity is located in photosynthetic organs, and ammonium in roots is assimilated mainly by Fd-independent NADH-GOGAT. Therefore, RFNR might have a limited impact on N assimilation in roots grown with nitrate or ammonium nitrogen sources. AtRFNR genes are rapidly induced by application of toxic nitrite. Thus, we tested the hypothesis that RFNR could contribute to nitrite reduction in roots by comparing Arabidopsis thaliana seedlings of the wild type with loss-of-function mutants of RFNR2 When these seedlings were grown under nitrate, nitrite or ammonium, only nitrite nutrition caused impaired growth and nitrite accumulation in roots of rfnr2 Supplementation of nitrite with nitrate or ammonium as N sources did not restore the root growth in rfnr2 Also, a scavenger for nitric oxide (NO) could not effectively rescue the growth impairment. Thus, nitrite toxicity, rather than N depletion or nitrite-dependent NO production, probably causes the rfnr2 root growth defect. Our results strongly suggest that RFNR2 has a major role in reduction of toxic nitrite in roots. A specific set of genes related to nitrite reduction and the supply of reducing power responded to nitrite concomitantly, suggesting that the products of these genes act co-operatively with RFNR2 to reduce nitrite in roots. © The Author 2016. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Strain-specific colonization pattern of Rhizoctonia antagonists in the root system of sugar beet.

PubMed

Zachow, Christin; Fatehi, Jamshid; Cardinale, Massimiliano; Tilcher, Ralf; Berg, Gabriele

2010-10-01

To develop effective biocontrol strategies, basic knowledge of plant growth promotion (PGP) and root colonization by antagonists is essential. The survival and colonization patterns of five different biocontrol agents against Rhizoctonia solani AG2-2IIIB in the rhizosphere of greenhouse-grown sugar beet plants were analysed in single and combined treatments. The study included bacteria (Pseudomonas fluorescens L13-6-12, Pseudomonas trivialis RE(*) 1-1-14, Serratia plymuthica 3Re4-18) as well as fungi (Trichoderma gamsii AT1-2-4, Trichoderma velutinum G1/8). Microscopic analysis by confocal laser scanning microscopy revealed different colonization patterns for each DsRed2/green fluorescent protein-labelled strain. Bacteria and T. velutinum G1/8 colonized the root surface and the endorhiza in single and co-culture, while for T. gamsii AT1-2-4, only the transfer of spores was observed. Whereas Pseudomonas strains formed large microcolonies consisting of hundreds of cells, S. plymuthica was arranged in small endophytic clusters or clouds around the entire root system. In co-culture, each strain showed its typical pattern and occupied specific niches on the root, without clear evidence of morphological interactions. PGP was only observed for four strains with rhizosphere competence and not for T. gamsii AT1-2-4. The results provide useful information on which combination of strains to test in larger biocontrol experiments directed to applications. © 2010 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

Feasibility of Lettuce Growth at Hypoxic and Sub-Ambient Total Gas Pressures

NASA Technical Reports Server (NTRS)

Hoffman, Anne

1997-01-01

Lettuce (Lactuca saliva L. cv. 'Waldmann's Green') plants were grown (1) either from seed to 5 days old to study the effect of low atmospheric pressure (70 kPa) on their germination and early growth, or (2) until maturity at 30 days old to determine any long-term growth effects. The data were compared to plants grown in a second matching chamber which was maintained at ambient pressure (101 kPa) that served as a control. In other experiments, plants were grown at ambient pressure until maturity and then subjected to low atmospheric pressure for periods of 24 hours to determine possible effects of intermittent low pressure. The O2 and CO2 partial pressures in the low pressure chamber were adjusted to levels equal to those in the ambient pressure chamber to prevent differences in plant response which would have resulted from differences in the partial pressure of those gasses. The O2 partial pressure in the ambient chamber was maintained at 21 kPa and provision was made for additional CO2 during the fight phase. The germination rate and early seedling growth were insensitive to a low pressure environment. The rate of root elongation of plants grown at 70 kPa and at 101 kPa was also approximately the same. The rate of net carbon assimilation (per unit leaf area) of plants grown at low atmospheric pressure was unaffected at all growth stages even though plants grown at 70 kPa had slightly greater fresh and dry weights. There were consistent differences in assimilate partitioning, as shown by higher root/shoot ratios of plants grown at low pressure. Transpiration rates of plants grown until maturity under either constant or intermittent low pressure were reduced. Dark respiration rates of plants grown until maturity under either constant or intermittent low pressure were approximately 20% higher than the control plants.

Growth enhancement of Quercus alba saplings by CO[sub 2] enrichment under field conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Norby, R.J.; O'Neill, E.G.; Wullschleger, S.D.

1993-06-01

White oak (Quercus alba L.) trees were grown in soil under field conditions for four growing seasons in open-top chambers containing ambient air continuously enriched with 0, 150, or 300 [mu]mol/mol CO[sub 2]. The trees were significantly larger in elevated CO[sub 2]: whole-tree mass (including woody roots) was 36% greater in +150 and 140% greater in +300 compared to ambient-grown trees. There were no significant effects of CO[sub 2] concentration on root-to-shoot or leaf area ratios. The stimulatory effect of CO[sub 2] occurred during seedling establishment, and there was no effect of CO[sub 2] on relative growth rate after themore » first field season. However, photosynthesis remained consistently higher in elevated CO[sub 2], foliar respiration was reduced, and fine root density and CO[sub 2] efflux from the soil were higher, as previously reported with yellow- poplar trees.« less

Vertical farming increases lettuce yield per unit area compared to conventional horizontal hydroponics.

PubMed

Touliatos, Dionysios; Dodd, Ian C; McAinsh, Martin

2016-08-01

Vertical farming systems (VFS) have been proposed as an engineering solution to increase productivity per unit area of cultivated land by extending crop production into the vertical dimension. To test whether this approach presents a viable alternative to horizontal crop production systems, a VFS (where plants were grown in upright cylindrical columns) was compared against a conventional horizontal hydroponic system (HHS) using lettuce ( Lactuca sativa L . cv. "Little Gem") as a model crop. Both systems had similar root zone volume and planting density. Half-strength Hoagland's solution was applied to plants grown in perlite in an indoor controlled environment room, with metal halide lamps providing artificial lighting. Light distribution (photosynthetic photon flux density, PPFD) and yield (shoot fresh weight) within each system were assessed. Although PPFD and shoot fresh weight decreased significantly in the VFS from top to base, the VFS produced more crop per unit of growing floor area when compared with the HHS. Our results clearly demonstrate that VFS presents an attractive alternative to horizontal hydroponic growth systems and suggest that further increases in yield could be achieved by incorporating artificial lighting in the VFS.

Draft Genome Sequence of a Kale (Brassica oleracea L.) Root Endophyte, Pseudomonas sp. Strain C9.

PubMed

Laugraud, Aurelie; Young, Sandra; Gerard, Emily; O'Callaghan, Maureen; Wakelin, Steven

2017-04-13

Pseudomonas sp. strain C9 is a plant growth-promoting bacterium isolated from the root tissue of Brassica oleracea L. grown in soil from Marlborough, New Zealand. Its draft genome of 6,350,161 bp contains genes associated with plant growth promotion and biological control. Copyright © 2017 Laugraud et al.

EFFECTS OF ELEVATED CO-2 AND N FERTILIZATION ON FINE ROOT DYNAMICS AND FUNGAL GROWTH IN SEEDLING PINUS PONDEROSA

EPA Science Inventory

The effects of elevated CO-2 and N fertilization on fine root growth of Pinus ponderosa Dougl. ex P. Laws. C. Laws., grown in native soil in open-top field-exposure chambers at Placerville, CA, were monitored for a 2-year period using minirhizotrons. The experimental design was a...

Control of cereal root pathogens with PGPR: The role of the natural antibiotic phenazine-1-carboxylic acid

USDA-ARS?s Scientific Manuscript database

Root pathogens are major agricultural impediments worldwide and must be controlled on the same or less arable land than currently available in order to meet the needs of the rapidly growing world population. In the Pacific Northwest (PNW) of the USA, where wheat is grown across a wide range of clima...

Root responses of Medicago truncatula plants grown in two different iron deficiency conditions: changes in root protein profile and riboflavin biosynthesis

USDA-ARS?s Scientific Manuscript database

Iron deficiency is a yield-limiting factor with major implications for field crop production in one-third of the world's agricultural areas, especially those with high soil CaCO3. A two-dimensional gel electrophoresis proteomic approach was combined with a study on the riboflavin synthesis pathway, ...

Human dermal papilla cells and outer root sheath cells: no follicular differentiation in nude mice and chicken embryos.

PubMed

Chiu, H C; Chang, C H; Jee, S H; Chang, C C; Wu, Y C

1994-09-01

Human scalp specimens were incubated in 5 U/ml dispase solution at 4 degrees C overnight before the isolation of dermal papillae and follicle epithelium. This pretreatment not only facilitated the attachment and cell outgrowth of dermal papillae but also made it easier to pluck out hairs with intact follicle epithelium. The outer root sheath cells were released from the follicle epithelium and grown on a feeder layer of mitomycin C-treated human dermal fibroblasts. The subcultured outer root sheath cells were grown in a serum-free medium. When the mixtures of early-passage dermal papilla cells and outer root sheath cells were injected into the subcutis of nude mice, an epidermal cyst surrounded by layers of fibrous tissue was found in three weeks. No hair follicles were found when the mixtures were implanted onto the chorioallantoic membrane of nine-day-old chicken embryos. A keratinized mass lying on the chorionic epithelium with or without smaller similar masses in the chorioallantoic membrane was found in eight days. No hair follicle-like structure could be found. Possible factors contributing to the failure to undergo follicular differentiation in this study are discussed.

Nitrogen affects cluster root formation and expression of putative peptide transporters

PubMed Central

Paungfoo-Lonhienne, Chanyarat; Schenk, Peer M.; Lonhienne, Thierry G. A.; Brackin, Richard; Meier, Stefan; Rentsch, Doris; Schmidt, Susanne

2009-01-01

Non-mycorrhizal Hakea actites (Proteaceae) grows in heathland where organic nitrogen (ON) dominates the soil nitrogen (N) pool. Hakea actites uses ON for growth, but the role of cluster roots in ON acquisition is unknown. The aim of the present study was to ascertain how N form and concentration affect cluster root formation and expression of peptide transporters. Hydroponically grown plants produced most biomass with low molecular weight ON>inorganic N>high molecular weight ON, while cluster roots were formed in the order no-N>ON>inorganic N. Intact dipeptide was transported into roots and metabolized, suggesting a role for the peptide transporter (PTR) for uptake and transport of peptides. HaPTR4, a member of subgroup II of the NRT1/PTR transporter family, which contains most characterized di- and tripeptide transporters in plants, facilitated transport of di- and tripeptides when expressed in yeast. No transport activity was demonstrated for HaPTR5 and HaPTR12, most similar to less well characterized transporters in subgroup III. The results provide further evidence that subgroup II of the NRT1/PTR family contains functional di- and tripeptide transporters. Green fluorescent protein fusion proteins of HaPTR4 and HaPTR12 localized to tonoplast, and plasma- and endomembranes, respectively, while HaPTR5 localized to vesicles of unknown identity. Grown in heathland or hydroponic culture with limiting N supply or starved of nutrients, HaPTR genes had the highest expression in cluster roots and non-cluster roots, and leaf expression increased upon re-supply of ON. It is concluded that formation of cluster roots and expression of PTR are regulated in response to N supply. PMID:19380419

Gravitropic mechanisms derived from space experiments and magnetic gradients.

NASA Astrophysics Data System (ADS)

Hasenstein, Karl H.; Park, Myoung Ryoul

2016-07-01

Gravitropism is the result of a complex sequence of events that begins with the movement of dense particles, typically starch-filled amyloplasts in response to reorientation. Although these organelles change positions, it is not clear whether the critical signal is derived from sedimentation or dynamic interactions of amyloplasts with relevant membranes. Substituting gravity by high-gradient magnetic fields (HGMF) provides a localized stimulus for diamagnetic starch that is specific for amyloplasts and comparable to gravity without affecting other organelles. Experiments with Brassica rapa showed induction of root curvature by HGMF when roots moved sufficiently close to the magnetic gradient-inducing foci. The focused and short-range effectiveness of HGMFs provided a gravity-like stimulus and affected related gene expression. Root curvature was sensitive to the mutual alignment between roots and HGMF direction. Unrelated to any HGMF effects, the size of amyloplasts in space-grown roots increased by 30% compared to ground controls and suggests enhanced sensitivity in a gravity-reduced environment. Accompanying gene transcription studies showed greater differences between HGMF-exposed and space controls than between space and ground controls. This observation may lead to the identification of gravitropism-relevant genes. However, space grown roots showed stronger transcription of common reference genes such as actin and ubiquitin in magnetic fields than in non-magnetic conditions. In contrast, α-amylase, glucokinase and PIN encoding genes were transcribed stronger under non-magnetic conditions than under HGMF. The large number of comparisons between space, ground, and HGMF prompted the assessment of transcription differences between root segments, root-shoot junction, and seeds. Because presumed transcription of reference genes varied more than genes of interest, changes in gene expression cannot be based on reference genes. The data provide an example of complex and different responses to microgravity conditions, induced curvature, ground controls, clinorotation, and magnetic field exposure.

Microbial Community Dynamics and Response to Plant Growth-Promoting Microorganisms in the Rhizosphere of Four Common Food Crops Cultivated in Hydroponics.

PubMed

Sheridan, C; Depuydt, P; De Ro, M; Petit, C; Van Gysegem, E; Delaere, P; Dixon, M; Stasiak, M; Aciksöz, S B; Frossard, E; Paradiso, R; De Pascale, S; Ventorino, V; De Meyer, T; Sas, B; Geelen, D

2017-02-01

Plant growth promoting microorganisms (PGPMs) of the plant root zone microbiome have received limited attention in hydroponic cultivation systems. In the framework of a project aimed at the development of a biological life support system for manned missions in space, we investigated the effects of PGPMs on four common food crops (durum and bread wheat, potato and soybean) cultivated in recirculating hydroponic systems for a whole life cycle. Each crop was inoculated with a commercial PGPM mixture and the composition of the microbial communities associated with their root rhizosphere, rhizoplane/endosphere and with the recirculating nutrient solution was characterised through 16S- and ITS-targeted Illumina MiSeq sequencing. PGPM addition was shown to induce changes in the composition of these communities, though these changes varied both between crops and over time. Microbial communities of PGPM-treated plants were shown to be more stable over time. Though additional development is required, this study highlights the potential benefits that PGPMs may confer to plants grown in hydroponic systems, particularly when cultivated in extreme environments such as space.

Pigeon Pea and Cowpea-Based Cropping Systems Improve Vesicular Arbuscular Mycorrhizal Fungal Colonisation of Subsequent Maize on the Alfisols in Central Malawi

PubMed Central

Semu, Ernest; Mrema, Jerome P.; Nalivata, Patson C.

2017-01-01

Mycorrhizal associations contribute to the sustainability of crop production systems through their roles in nutrient cycling and other benefits in the soil-plant ecosystems. A two-year study was conducted on the Alfisols of Lilongwe and Dowa districts, Central Malawi, to assess the vesicular-arbuscular mycorrhizal (VAM) fungal colonisation levels in pigeon pea, cowpea, and maize grown in sole cropping, legume-cereal, and legume-legume intercropping systems and in the maize grown in short rotation (year 2) as influenced by the previous cropping systems and N fertilizer application. The gridline intersect method was used to assess the VAM fungal colonisation levels. Results showed that all treatments that included legumes whether grown as sole crop, in legume-cereal or in legume-legume cropping systems in the previous year, had significantly higher (P < 0.05) VAM fungal colonisation of the rotational maize crop roots by a range 39% to 50% and 19% to 47% than those in maize supplied and not supplied with N fertilizer, respectively, in a maize-maize short rotation, at the Lilongwe site. A similar trend was reported for the Dowa site. Furthermore, there were positive correlations between VAM fungal colonisation and the plant P content, dry matter yield, and nodule numbers. Further studies may help to assess the diversity of VAM fungal species in Malawi soils and identify more adaptive ones for inoculation studies. PMID:28584528

Pigeon Pea and Cowpea-Based Cropping Systems Improve Vesicular Arbuscular Mycorrhizal Fungal Colonisation of Subsequent Maize on the Alfisols in Central Malawi.

PubMed

Njira, Keston O W; Semu, Ernest; Mrema, Jerome P; Nalivata, Patson C

2017-01-01

Mycorrhizal associations contribute to the sustainability of crop production systems through their roles in nutrient cycling and other benefits in the soil-plant ecosystems. A two-year study was conducted on the Alfisols of Lilongwe and Dowa districts, Central Malawi, to assess the vesicular-arbuscular mycorrhizal (VAM) fungal colonisation levels in pigeon pea, cowpea, and maize grown in sole cropping, legume-cereal, and legume-legume intercropping systems and in the maize grown in short rotation (year 2) as influenced by the previous cropping systems and N fertilizer application. The gridline intersect method was used to assess the VAM fungal colonisation levels. Results showed that all treatments that included legumes whether grown as sole crop, in legume-cereal or in legume-legume cropping systems in the previous year, had significantly higher ( P < 0.05) VAM fungal colonisation of the rotational maize crop roots by a range 39% to 50% and 19% to 47% than those in maize supplied and not supplied with N fertilizer, respectively, in a maize-maize short rotation, at the Lilongwe site. A similar trend was reported for the Dowa site. Furthermore, there were positive correlations between VAM fungal colonisation and the plant P content, dry matter yield, and nodule numbers. Further studies may help to assess the diversity of VAM fungal species in Malawi soils and identify more adaptive ones for inoculation studies.

Distribution pathways of hexachlorocyclohexane isomers in a soil-plant-air system. A case study with Cynara scolymus L. and Erica sp. plants grown in a contaminated site.

PubMed

Pereira, R Calvelo; Monterroso, C; Macías, F; Camps-Arbestain, M

2008-09-01

This study focuses on the main routes of distribution and accumulation of different hexachlorocyclohexane (HCH) isomers (mainly alpha-, beta-, gamma- and delta-HCH) in a soil-plant-air system. A field assay was carried out with two plant species, Cynara scolymus L. and Erica sp., which were planted either: (i) directly in the HCH-contaminated soil; or (ii) in pots filled with uncontaminated soil, which were placed in the HCH-contaminated soil. Both plant species accumulated HCH in their tissues, with relatively higher accumulation in above-ground biomass than in roots. The beta-HCH isomer was the main isomer in all plant tissues. Adsorption of HCH by the roots from contaminated soil (soil-->root pathway) and adsorption through the aerial biomass from either the surrounding air, following volatilization of the contaminant (soil-->air-->shoot pathway), and/or contact with air-suspended particles contaminated with HCH (soil particles-->shoot pathway) were the main mechanisms of accumulation. These results may have important implications for the use of plants for reducing the transfer of contaminants via the atmosphere.

Effect of silicon fertilizers on cadmium in rice (Oryza sativa) tissue at tillering stage.

PubMed

Ji, Xionghui; Liu, Saihua; Juan, Huang; Bocharnikova, Elena A; Matichenkov, Vladimir V

2017-04-01

Silicon has been found to enhance the plants' tolerance to heavy metal stress. In a field study, the effect of different types of Si-rich soil amendments (slag, ground slag, and diatomaceous earth) and fertilizers (activated slag, ground activated slag, and commercial Si fertilizer) on the distribution of soluble and insoluble forms of Cd in the rice plant organs grown on long-term cultivated paddy soil contaminated with Cd (central part of Hunan Province, China) was investigated. The soluble Si and Cd were tested in the apoplast and symplast of the roots, stems, and leaves of rice at a tillering stage. The Si-rich materials increased rice biomass by up to 15.5% and reduced the total leaf Cd by 8.5 to 21.9%. Commercial Si fertilizer was the most effective. Three main locations of the most active Si-Cd interactions were distinguished in the soil-plant system: soil, where monosilicic acid affords adsorption and fixation of the bioavailable Cd and root apoplast and apoplast above roots, where monosilicic acid can precipitate Cd. The transport of Cd to stems and leaves and the mobility of Cd in the soil depend on the content of monosilicic acid in the system.

Distribution of gelatinous fibers in seedling roots of living cycads.

PubMed

Magellan, Tracy M; Griffith, M Patrick; Tomlinson, P Barry

2015-08-01

• The presence of gelatinous (tension) fibers (GFs) in the roots of two extant cycadales (Cycas and Zamia) in a recent publication raises interesting issues of GF distribution in seed plants. An immediate question that arises from this discovery is whether GFs occur consistently in the radicle of all extant cycad genera and therefore might have a similar role in root contraction. We present results of a survey of nursery-grown material of all 10 genera.• We sequentially sectioned seedling root material and used simple staining and histochemical methods to follow anatomical changes along the radicle of all 10 genera.• We found GFs in nine genera; Stangeria appears to be the only genus without them. In all genera, there is a wide variation in the number of GFs and also variation in the development of thickened, fleshy roots. "Tertiary expansion" is a useful term to describe late cell division and enlargement of both primary and secondary parenchyma, the latter produced by the vascular cambium. Certain other histological features can be diagnostically useful at the generic level.• The functional interpretation of GFs as being wholly responsible for apparent tissue contraction is now somewhat compromised, especially as distortion of tracheary elements by changes in dimensions of parenchyma cells can falsely suggest root contraction when it may not occur. These preliminary results point the way to a more precise investigation of study material grown in more uniform environments using advanced technological methods. © 2015 Botanical Society of America, Inc.

Influence of Common Bean (Phaseolus vulgaris) Grown in Elevated CO2 on Apatite Dissolution

NASA Astrophysics Data System (ADS)

Olsen, A. A.; Morra, B.

2016-12-01

We ran a series of experiments to test the hypothesis that release of plant nutrients contained in apatite will be accelerated by the growth of Langstrath Stringless green bean in the presence of atmospheric CO2 meant to simulate possible future atmospheric conditions due a higher demand of nutrients and growth rate caused by elevated CO2. We hypothesize that elevated atmospheric CO2 will lead to both increased root growth and organic acid exudation. These two traits will lead to improved acquisition of P derived from apatite. Experiments were designed to investigate the effect of these changes on soil mineral weathering using plants grown under two conditions, ambient CO2 (400ppm) and elevated CO2 (1000ppm). Plants were grown in flow-through microcosms consisting of a mixture of quartz and apatite sands. Mini-greenhouses were utilized to control CO2 levels. Plant growth was sustained by a nutrient solution lacking in Ca and P. Calcium and P content of the leachate and plant tissue served as a proxy for apatite dissolution. Plants were harvested biweekly during the eight-week experiment and analyzed for Ca and P to calculate apatite dissolution kinetics. Preliminary results suggest that approximately four times more P and Ca are present in the leachate from experiments containing plants under both ambient and elevated CO2 levels than in abiotic experiments; however, the amounts of both P and Ca released in experiments conducted under both ambient and elevated CO2 levels are similar. Additionally, the amount of P in plant tissue grown under ambient and elevated CO2 conditions is similar. Plants grown in elevated CO2 had a greater root to shoot ratio. The planted microcosms were found to have a lower pH than abiotic controls most likely due to root respiration and exudation of organic acids.

Effect of different cultural systems on antioxidant capacity, phenolic content, and fruit quality of strawberries (Fragaria x aranassa Duch.).

PubMed

Wang, Shiow Y; Millner, Patricia

2009-10-28

The effect of cultivation practices for controlling strawberry black root rot (BRR) on fruit quality, antioxidant capacity, and flavonoid content in two strawberry cultivars Allstar and Chandler (Fragaria x ananassa Duch.) was evaluated. Strawberry fruits used in this study were from plants grown in soils which had a prior history of BRR and red stele, and had not been fumigated during the seven years prior to the study. Results from this study showed that fruit from plants grown in compost socks had significantly higher oxygen radical absorbance capacity (ORAC), flavonoids, anthocyanins, soluble solids content (SSC), titratable acid (TA), fructose, glucose, sucrose, malic acid, and citric acid than fruit produced in the black plastic mulch or matted row systems. Cultivar Chandler surpassed cv. Allstar in sugar content, acid content, and flavonoid content regardless of preplanting vinegar drenching and various culture treatments. However, preplanting vinegar treatment increased cyanidin-based and pelargonidin-based anthocyanins but decreased sugar content in fruits of both cultivars.